sandmote
2023-12-20, 03:45 PM
This page on the homebrewery (https://homebrewery.naturalcrit.com/share/PwtF_W73QWvR)
I had a thread for a bunch of plant based traps for the outer planes, and here I've made some for the inner planes as well. Given there's a slightly greater focus on explaining how these plants survive on the inner planes in the first place, I don't think the traps turned out quite as interesting, but at least these give some additional interest to the planes. Please note these traps are based on the elemental planes as presented in the 5e DMG, which breaks the main four elemental planes into separate regions.
Cash Crops:
With two on the plane of fire and two on the plane of air, I expect there to be a very different culture regarding the two. The Djinn are chaotic good, meaning they likely have individualized groves or gardens of these plants. The Chaotic Evil Efreet, in contrast, probably run brutal plantations to harvest larger quantities of the plant. You could maybe have an adventure around that, where a good aligned elemental needs medicine, but also wants it ethically sourced.
Intermediate trap (level 5-10, deadly threat)
The sap of myrrh trees is thick and quickly forms thick, chunky sap when exposed to air, much like blood clotting. The floating myrrh trees native to the plane of air produce distinctly stronger and more pungent sap, which is difficult to collect on account of the vicious spikes covering the tree’s surface, and the dificulty of holding still to collect the sap on the ever shifting plane.
Trigger. The thorns are triggered when creatures flies, is blown, or falls into the tree’s space, or the tree falls into a creature. The sap is triggered when the tree takes at least 5 points of slashing or acid damage as well as when it is burned.
Effects. The spines of the tree pierce deep into passing creatures, and the sap inflicts a pleasant state while harming the vectors of disease.
Thorns. A creature which interacts with the thorns must make a DC 15 Dexterity saving throw, taking 4d6 piercing damage on a failed save or half as much on a success. a creature attempting to grab onto the tree has disadvantage on the saving throw, while one attempting to climb the tree once it has attached itself has advantage on the saving throw.
Sap. The sap of the floating myrrh tree has medicinal properties, but is harmful when fresh or in high doses. When taking more than 4 doses in a 24 hour period a creature must make a DC 20 Constitution saving throw. On a failed save the creature takes 4d4 poison damage and has disadvantage on Constitution checks and saving throws for 24 hours. On a success the creature takes half as much damage and has disadvantage on Constitution checks for 8 hours instead. When a cut strong enough to trigger the tree is made, each creature within 5 feet of the cut must make the same saving throw, after which 2d4 pieces of myrrh can be harvested from the cut.
Prepared Compounds. Breathing in myrrh smoke for at least 1 minute grants you advantage on your next saving throw against any poison or disease affecting you.
When applied to a creature that has lost hit points within the last minute, myrrh causes the creature to heal 1d6 hit points, up a maximum of the number of hit points it lost in that period. The creature then cannot benefit from myrrh in this manner for 1 minute or until it takes damage. Applying the myrrh requires a successful DC 10 medicine check.
If a creature ingests 5 pieces of myrrh over a short or long rest, it must make a saving throw as described in the sap section, but all poisons ingested by the creature end at the end of the rest.
Myrrh from mundane plants on the material plane typically sell for 25 gold per pound. Myrrh from the floating myrrh trees of the plane of air are much more potent and typically yields a price of 25 gp per piece.
Countermeasures. A creature can notice the sharp spines of the floating myrrh tree with a successful DC 5 Perception (Wisdom) check, and identify it as a myrrh tree with a successful DC 10 Nature (Intelligence) check.
The tree has an AC and saving throws equivalent to those of an Awakened Tree, although it is an inanimate, nonmagical plant.Simple trap (level 1-4, moderate threat)
A flower whose large stamens produce a pleasant tingling sensation and a give food a light blue color when mixed in, static saffron is the most valuable export produced on the plane of air. It is most often pollinated by sky bees, which are also native to the plane and immune to lighting damage. With blooms a foot across they are often kept for decoration and honey production even if not used to collect spice. The plane’s djinn prefer servants to forced labor, but still push for production from shockers and others able to safely harvest the stamens. Unlike true saffron, the plants are capable for producing seeds, but the spice is collected from the portion of the flower responsible for starting this process rather than one one which produces pollen.
Trigger. A creature attempts to pick the three inch long stamens from a static saffron flower.
Effect. The creature must make a DC 10 Constitution saving throw, taking 1d10 lightning damage on a failure or half as much on a success.
Blooming year round, a 10 foot patch of static saffron contains 4d4 flowers at any given time. 10 flowers produce enough for 1 fluid ounce of static saffron, which sells for 100 gp.
Countermeasures. A successful DC 10 Survival (Wisdom) check allows a creature to identify the stamens of the flower as edible. If a creature succeeds on the check by 10 or more, or succeeds on a DC Investigation (Intelligence) check studying insects on the flower identifies the stamens electrocute when disturbed.Simple trap (level 5-10, dangerous threat)
The blooms of radiant poppies release dangerous amounts of harmful light, which withers and scorches even creatures immune to extreme heat. Grown for their narcotic sap radiant poppies are fully effective for elementals otherwise immune to poison. A creature can spend 1 minute harvesting immature seed pods from a 5 foot square of poppies, collecting 50 gp worth of sap from the square if the poppies are in full bloom or half as much from one finished blooming.
Trigger. A radiant poppy’s blooms affect any creature within 5 feet of a patch of radiant poppies in bloom.
Effects. Radiant poppies inherently harm nearby life, but are grown for their effects on elementals and other creatures.
Blooms. A creature which enters or starts its turn in a 5 foot square of blooming radiant poppies must make a DC 15 Constitution saving throw, taking 1d4 radiant damage on a failed save or half as much on a success.
Prepared Compounds. A creature can prepare 1 dose of knockout draught from 50 gp worth of radiant poppy sap and 25 gp worth of additional materials, subject to the normal crafting rules. One draught sells for 150 gp. A creature that ingests this compound must make a DC 15 Constitution saving throw or fall unconscious for 1 minute, until the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake. Elementals cannot benefit to immunity to poison against this effect.
Countermeasures. A creature can identify there is something off about the poppy’s space with a successful DC 5 Perception (Wisdom) check, and identify radiant poppies with a successful DC 15 Nature (Intelligence) check.
Destroying the Patch. Radiant poppies are immune to fire, piercing, psychic, and radiant damage and has vulnerability to effects dealing damage to an area. A 5 foot square of poppies has 10 (4d4) hit points.Simple trap (level 5-10, deadly threat)
Where black pepper is spicy to ward off mammals from eating its seeds, white pepper seeks to avoid being messed with by fire elementals on the plane on which it grows. Still occasionally found wild on the plane white pepper is a delicacy and a prize export from the plane of fire. The plants resemble black pepper, but with much thicker vines and leaves, and peppercorns half an inch across. The Efreet are the largest producers of white pepper, having massive numbers of slaves to harvest and process it. A 10 foot square of white pepper plants produces about 50 peppercorns, which weigh 1 pound. White pepper is worth 300 gp per pound when processed, and half as much unprocessed.
Trigger. A creature cuts into a portion of the white pepper plant, including to harvest peppercorns, or bites into the peppercorn.
Effects. The cooling substances that allow white pepper to grow on the plane of fire erupt in frost when disturbed, and are packed into the peppercorns with a much greater density. When triggered, the triggering creature must make a DC 20 Constitution saving throw, as the air around the cut momentarily freezes solid. The triggering creature takes 8d10 cold damage on a failed save, or half as much on a success.
A creature which has proficiency with the herbalism kit gains a bonus to its saving throw equal to its proficiency bonus to its saving throw when harvesting peppercorns by hand.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify white pepper. A DC 10 Survival (Wisdom) or DC Perception (Wisdom) saving throw allows a creature to notice the relative cold in the plant’s space.
Limited Frost. Once triggered, a peppercorn’s frost is expended. A 5 foot portion of live plant regains the ability to deal cold damage at the site of cuts at the rate of 1d10 per hour, to a maximum of 8d10.
Other Flora:
Some of these are based on real plants (primarily on the plane of water) but the others fill some niche. For instance, the stonecatcher vine can form a location for a PC to land if they fall away from the party. It help that, the stonecatcher can catch the PC itself, making it harder for the PC to miss. Ironthorn, on the other hand, is a hassle to kill and was written to justify why the plane of earth can have a surface but the mines all still run underground for their full length.
Simple trap (level 5-10, moderate threat)
Mostly isolated to Mistral Reach, various epiphytes tossed into the plane over the centuries have adapted to the environment. Some float toward surfaces from which to gather moisture and nutrients, but the beating epiphyte bats away both potential grazers and other surfaces.
Trigger. A creature or object touches the epiphyte.
Effect. One of the epiphyte's stems lashes out at the target with a +4 to hit bonus. On a hit, the target takes 2d6 bludgeoning damage and must make a DC 10 Wisdom saving throw. On a failed save the target loses track of which way is down for 1 minute and start falling in a random direction. At the end of each of its turns the target can repeat the saving throw, ending the effect on a success.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the epiphyte’s stems are capable of motion. A stem can be severed with a successful weapon attack against an AC of 15, which must deal at least 5 points of acid, bludgeoning, or fire damage.Intermediate trap (level 1-4, deadly threat)
While the largest earthbound settlements on the plane of air are found on the largest motes of stone found, there also exist patches of smaller rocks bound together by stonecatcher vines, which grab onto passing falling objects in search of additional nutrients. Stonecatcher vines can form patches over a hundred feet across, providing habitat for various flying insects and small birds whose ancestors became trapped on the plane long ago.
Trigger. An object of small size or larger passes within 5 feet of the vine while moving at a speed of 60 feet per round.
Effect. The vine strikes out at the object. The vine has an attack modifier of +12. On a hit the vine deals 4d6 bludgeoning damage and the target is grappled by the vine. A medium or smaller target is restrained while grappled in this manner. If the target is huge or larger the grappling vine is severed from the main plant and remains grappling the target. In 1 hour the severed vine grows enough roots to bind it to a grappled object made of stone, wood, or flesh.
Countermeasures. A successful DC 10 Nature (Intelligence) check reveals the nature of the vine.
Escaping the Vine. A grappled creature can free itself from the vine with a successful DC 20 Acrobatics (Dexterity) check or Athletics (Strength) check.
Removing the Vine. A creature can dislodge a 5 foot section of grappling stonecatcher vine from the surface attached to it with a successful DC 20 Athletics (Strength) check. Removing the roots of a stonecatcher vine requires a DC 20 check with carpenter’s tools to remove each root; a 5 foot section of stonecatcher vine will have 2d4 roots holding it to the surface it grows on.Simple trap (level 5-10, deadly threat)
An unassuming bush only marked by the lack of other vegetation within 1 foot of its leaves, the alchemy plant produces sugar by converting nearby substances into the necessary component parts. It survives by transforming itself and neighboring objects into whatever it expects them to find inedible; attempts to bite the plant see it turn to worthless stone and attempts to cut it see it become steel.
Trigger. A creature touches the alchemy plant, an object touches the plant, or two inanimate objects touch the plant.
Effects. The alchemy plant reacts differently based on the number and types of objects touching it.
Flesh and Bone. When touched by living material, the alchemy plant turns to stone until the contact ends. If contact lasts more than a full round, the touching creature must make a DC 20 Dexterity saving throw. The limb of the creature that fails the save begins to turn to stone and a creature of tiny size is restrained. A target creature must repeat the saving throw at the end of its next turn, with its limb turning to stone and becoming unusable, or becoming petrified if it is a tiny creature.
One object. While in contact with one object, the alchemy plant turns to the same substance, turning to whichever material is being used to try to cut it, or stone if touched by the denizens of the plane.
Two objects. When a second object touches the alchemy plant, there is a 50% chance that either object is converted to the substance of the other over the course of the next round. The quantity of either object converted is of equal size to the smaller of the two objects.
Countermeasures. A creature can identify an alchemy plant with a successful DC 20 Nature (Intelligence) check.
Picking the Plant. The plant requires concentration to transmute its own form (as if Concentrating on a spell). A creature can uproot the alchemy plant with a successful DC 20 Strength check, killing the plant instantly. Objects and creatures being converted by the plant only cease to be transmuted if the plant is killed in the round during which they are transmuted.
Restoration. A creature restrained by the alchemy plant’s effect or a limb converted within the last round can be healed and the effect ended using the lesser restoration spell, the remove curse spell, or stronger magic. A fully petrified creature remains petrified until it is freed by the greater restoration spell or other magic which can end the condition.Intermediate trap (level 5-10, dangerous threat)
One the material plane, there are species across most major groups of fungi which prey on nematodes, some by snaring them in ring like growths, spread out to effectively catch prey struggling to escape. The relatives of these fungi on the plane of earth are massive, able to wrap themselves around creatures of even medium size to feed.
Trigger. A creature touches one of the fungus’s snares.
Effects. The fungus maintains methods to strengthen its grip on captured prey as it struggles.
Capture. The snare springs shut, and the target must make a DC 10 Dexterity saving throw or be restrained by the trap. A trapped creature can make a DC 10 Athletics (Strength) or Acrobatics (Dexterity) check to try to escape the trap. Additionally, a creature within 5 feet of the restrained creature can attempt a DC 10 Athletics (Strength) check, freeing the target on a success.
Escalation. When a creature fails on its check to free a creature from the fungus or to sever a snare, the creature triggers an additional snare within 5 feet of the first. A creature must escape each snare restraining it separately.
Quell. A creature which starts it turn restrained by the fungus takes 1d6 bludgeoning damage for each snare restraining it.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the fungal snare.
Killing the Fungus. A snare an be severed with a successful attack dealing at least 10 points of slashing or acid damage to the snare, which has an AC of 10. If targeted with a blight spell, a 10 foot patch of fungus is destroyed.Simple trap (level 5-10, dangerous threat)
Growing in thin, vertical spikes on the plane of earth, ironthorn plants can grow up to 3 feet straight up, absorb massive amounts of iron from the surrounding environment with their wide roots, making the plants incredibly resistant to grazing. Patches established on top of iron deposits on the material plane often prove difficult to remove. Thankfully, the surface of the plane of earth is one of the few places with enough iron to sustain a population of ironthorn of any significant size. Unfortunately, digging even a few feet through ironthorn plants can prove harder than mining iron elsewhere.
Trigger. The ironthorn is dangerous to enter, and more dangerous to try digging through.
Trampling. A creature steps into the ironthorn’s space.
Digging. A creature attempts to sever the stem or roots if the ironthorn, such as by attacking it.
Effect. The edges and blades of the ironthorn are razor sharp, and the wiry plant resists attempts to sever it to an extreme extent.
Trampling. The triggering creature must make a DC 15 Dexterity saving throw. On a failed save the creature takes 4d8 piercing damage and 2d8 slashing damage. The creature takes half as much damage on a success.
Digging. The triggering creature must make the saving throw as against trampling the ironthorn. If using a nonmagical weapon or tool the item takes 3d6 damage, ignoring its AC.
Countermeasures. A creature can identify ironthorn with a successful DC 15 Nature (Intelligence) check. A creature can identify the plant is extremely sharp with a successful DC 5 Survival (Wisdom) check.
Destroying the Plant. A 5 foot patch of ironthorn has 150 hit points, immunity to lightning, piercing, and psychic damage and resistance to all other damage types except necrotic and slashing damage. It withers and dies instantly if targeted with the blight spell. Once killed the remaining dead roots have 100 hit points, immunity to lightning, necrotic, piercing, poison, and psychic damage, and resistance to all other damage types except slashing damage.Intermediate trap (level 5-10, dangerous threat)
Plants resembling massive pitchers, cauldron plants desperately try to grab and digest any trace of water they can find on the plane of fire where they grow.
Trigger. A creature walks within 5 feet of the cauldron plant.
Effects. The plant attacks with a +5 bonus to the attack roll. On a hit the plant deals 11 (2d10) piercing damage and grapples the target. Until this grapple ends the plant can’t attack another target.
A creature can make a DC 15 Strength (Athletics) check, freeing itself from the plant and ending the condition on a success. A creature can also make this check to free another creature within reach of the cauldron plant.
Swallow (Initiative 10). The plant attacks with a +5 bonus to the attack roll. On a hit the target takes 11 (2d10) piercing damage, 10 (4d4) acid damage, and becomes restrained by the cauldron plant.
Dissolve (Initiative 10). A creature that starts its turn restrained by the cauldron plant takes 20 (8d4) acid damage.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify a cauldron plant.
Attacks. The cauldron plant has an AC of 8. Each attack dealing at least 5 points of slashing damage to the cauldron plant reduces the plant’s attack bonus and the DC to escape the plant by 2. The plant’s pot becomes too shredded to grapple if its attack bonus is reduced to +0.Simple trap (level 5-10, moderate threat)
Marked by its 10 foot tall bundle of leaves and the smaller plants growing around its base, the static burster unleashes bolts of lightning at creatures which move past, its foot long ashen leaves turning bright amber as it does so.
Trigger. A creature of small size or larger passes within 10 feet of the static burster’s base or an object weighing 20 pounds or larger strikes the plant or the ground within 10 feet.
Effects. The plant unleashes a blast of lightning in a 1 foot wide, 20 foot long arc of lighting in the direction of the triggering creature or object. Each creature in the line’s space must succeed on a DC 15 Dexterity saving throw or take 21 (6d6) lightning damage. A full grown static burster has 2d6+3 leaves, each growing 10 feet tall in the plant’s space.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify a static burster.
Discharge. Each leaf of the plant can hold up to one charge, and turns bright amber when it discharges lightning. Once discharged, the leaf rebuilds this charge by 1d6 each hour, turning fully ashen when it reaches a full charge of 6d6 lightning damage.
Severing. Each of the leave’s stems has 5 (2d4) hit points, and immunity to fire, lightning, piercing, and psychic damage. It can also be torn off with a DC 20 Athletics (Strength) check. A severed leaf’s maximum charge is reduced to 10 (3d6) lightning damage, which it discharges when it hits the ground or is touched by a creature. A severed leaf can’t regain charge.Intermediate trap (level 5-10, dangerous threat)
Growing in the endless flowing surface of the plane of ooze, clambering mangroves wrap their roots around whatever solid objects they encounter, staying above the muck by grabbing wreckage, wood, and creatures and pushing them below itself.
Trigger. A creature or object knocks against the mangrove’s roots.
Effects. A triggering object is grappled by the mangrove. A triggering creature must make a DC 15 Acrobatics (Dexterity) or Athletics (Strength) check (its choice). On a failed check the creature is restrained by the mangrove. A grappled creature can repeat the check, escaping the tree on a success. A creature can attempt a DC 15 Athletics (Strength) check to free a grappled target, but must avoid being grappled by the mangrove before it can attempt the check.
A creature that starts its turn grappled by the mangrove must make a DC 15 Constitution saving throw, taking 4d6 bludgeoning damage on a failed save. A creature knocked unconscious is pushed underwater, where it risks drowning.
Countermeasures. A DC 15 Nature (Intelligence) check allows a creature to identify the tree. A mangrove’s root can be severed by dealing at least 10 points of slashing or acid damage to it with a single attack action.Simple trap (level 5-10, moderate threat)
Snapweed is named for the eruption of the seed pods, which can extend multiple feet in the varieties found on the prime material. Instant snapweed, native to the plane of ooze, grows to full height and flings its seeds almost as quickly, with enough force to send many creatures fleeing for safety.
Trigger. Any creature that enters the area of instant snapweed seeds must succeed on a DC 15 Dexterity saving throw or trigger the trap.
Effects. For 1 round after being triggered, the snapweed grows to 3 feet in height. On initiative count 10 of the next round, the snapweed bursts, flinging seeds in a 20 foot long cone in the direction of the triggering creature. The ground below the cone becomes covered in instant snapweed seeds, which become mature enough to be triggered after soaking in water for 24 hours.
Each creature in the cone’s space must make a DC 10 Dexterity saving throw, taking 2d6 bludgeoning damage on a failed save or half as much on a success.
Countermeasures. A DC 20 Nature (Intelligence) check allows a creature to identify the seeds of instant snapweed, and a DC 10 Nature (Intelligence) check allows a creature to identify instant snapweed while it is growing.
Instant snapweed seeds are killed if subject to an area which deals fire or cold damage. A creature can spend 1 minute clearing a 5 foot square of snapweed seeds. If the seeds are mature the creature must make a saving throw to avoid triggering a trap.Simple trap (level 1-4, dangerous threat)
Sometimes nicknamed the “little apple of death,” manchineel trees contain highly toxic sap throughout, even on the fruit, potent enough to blister the skin if rain washes it onto you. A number of these plants survive on islets on the plane of water, preventing habitation where they grow.
Trigger. A creature makes a melee attack targeting the tree, stands under the tree in the rain, or stands within smoke from fresh Manchineel wood.
Effects. The triggering creature must make a DC 15 Constitution saving throw. On a failed save the creature takes 2d4 acid damage and is blinded for 1 minute. On a success the creature takes half as much damage and isn’t blinded.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the tree. If burnt at the base the tree can be felled, after which the sap takes 1 week to dry. Once dried the wood can be used safely.Simple trap (level 5-10, moderate threat)
Of the threats found in the sea, red tide may be one of the most insidious. Born from massive swells in the populations of local algae, which often produce toxins and drain the oxygen from the water. The most common variety of red tide found on the plane of water is highly toxic, killing wide swaths of native marine life when it takes over the area.
Trigger. The effects of red tide become more severe the longer a creature spends time in it.
Inhalation. A creature enters the area of the red tide or the tide drifts into the creature’s space. A creature which does not need to breath or which has protection from inhaling the surrounding water does not trigger the red tide.
Extended Inhalation. For every 2 hours a creature spends in contact with red tide in a 24 hour period, it must make an additional DC 5 Constitution saving throw.
Effects. On each turn, on initiative count 0 the tide flows with the current, typically 10 feet per round.
Inhalation. When a creature enter’s the area of the red tide it must make a DC 5 Constitution saving throw. On a failed save, the target has disadvantage on Constitution saving throws against inhaled poisons, diseases, and gasses for 2d4+2 hours.
Extended Inhalation. When a creature fails its subsequent saving throw against red tide, it becomes poisoned for 24 hours. If the creature was already poisoned in this manner, it instead gains 1 level of exhaustion.
Countermeasures. Red Tide an be identified with a successful DC 10 Nature (Intelligence) check. Creatures which don’t breath or which avoid breathing in the water afflicted with red tide do not trigger it. Unfortunately, killing red tide fails to remove or purify the area of the toxins.
Self Protection. The amount of poison produced by red tide is minimal, and granting a creature advantage on saving throws against the tide can greatly extend how long a creature can travel through it. Many creatures living on the plane of water also accumulate items which help produce water or control its flow, allowing them beat away sections of red tide and create clean water to breathe.
Elemental Phenomena Looking Like Plants:
The lore of elementals take the form of animals is older, so I figured there should be elemental entities which also resemble plants.
Simple trap (level 5-10, dangerous threat)
Vertical icicles bearing masses of sharp frost, creatures standing beneath so-called “frost pines” are in danger of being sprayed by shards of ice while standing beneath them. They grow in groves on the plane of ice, but where the vegetation in taiga provides cover and nutrients, passing inside frost pines only risks being struck with a hail of needles. For reasons still debated by scholars, frost pines reach a uniform height of 30 feet tall.
Trigger. A creature or object strikes the icicle dealing damage other than fire, poison, or psychic damage, or an effect which moves either the surface beneath the pine or the pine itself.
Effect. The area in a 10 foot wide, 30 foot tall cylinder originating from the top of the pine explodes with thousands of tiny needles. Creaures in the cylinder’s space must make a DC 15 Dexterity saving throw. On a failed save each creature takes 3d6 piercing damage and 1d6 cold damage. On a success the target takes half as much damage.
Countermeasures. A triggered frost pine takes 4 hours to regrow its needles, during which the size of the eruption is reduced. After 1 hour the pine deals 1d6 cold damage when triggered, and deals 1d6 additional piercing damage for each additional hour it is left to grow.
Fire Damage. If an area of the icicle takes fire damage, the icicles in that area melt and reduce the damage dealt by the tree by 1d6 for every 5 points of damage. The pine has vulnerability to fire.Simple trap (level 5-10, moderate threat)
Native to the plane of fire, choking willows grow on the banks of lava flows on their way from the fountains of creation to the sea of fire. The branches bend down over the streams they grow from, their small leaves smoking slightly. When disturbed by the wind or shaken, the trees release bursts of smoke, warding off creatures and sending pollen floating on the breeze.
Trigger. The tree is exposed to moderate wind (10 miles per hour or higher) or shaken be the creature.
Effects. The tree emits dense smoke in a 15-foot-radius, 30-foot-high cylinder around the tree. The smoke spreads around corners, and its area is heavily obscured. It lasts for 10 minutes or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.
Each creature that starts its turn or enters the smoke during its turn must make a DC 10 Constitution saving throw. On a failed save the target gains one level of exhaustion and is blinded for 10 minutes.
Countermeasures. A DC 15 Nature (Intelligence) check allows a creature to identify the tree. Once a tree has been triggered, it won’t release smoke again for 1 hour. An area of effect dealing acid or lightning damage prevents the tree from emitting smoke in the area the two effects would overlap, taking the tree 1 week to regrow.Simple trap (level 5-10, moderate threat)
Jets of fresh water naturally form on the plane of water, not only spraying up from the surface on the water, but also where water of different salinities meets in the darkened depths. Nicknamed sweetwater maples on account of their treelike shape and how they can be tapped for fresh water, they are a critical resource for surface dwellers crossing the plane. Groups of these waterspouts, referred to as groves, are important resources on the plane, and the largest and finest groves produce large quantities of pure water, which sells for as much as wine due to its resistance to spoiling. Different groves produce water with slightly different taste, and some marids run wateries with produce selling up to 15 gp per bottle. Unlike wine, aging sweetwater maple “sap” has no effect.
Trigger. The vortex of the maple produces a constant cone of rushing water, pointed straight up, stemming from a central trunk up to 5 feet wide and 10 feet tall. A creature triggers the maple when passing through the canopy or first inserts a spout into the trunk, which look much like the taps drilled into maple trees.
Effect. The triggering creature must make a DC 10 Strength saving throw, taking 2d10 bludgeoning damage on a failed save or half as much on a success. If a creature attempting to insert a tap fails the saving throw, it also fails to insert the tap.
Countermeasures. A creature can identify sweetwater maples as a source of clean drinking water with a successful DC 15 Survival (Wisdom) check. A creature has advantage on this check if it has tasted the spray from maple.
Controlling Water. Effects which control water can slow a sweetwater maple’s flow. Instantaneous effects, such as the shape water spell, can slow the jet for 1 round, and lasting effects, such as the control water spell affect the jet for the duration. While the rate of flow is slowed the damage dealt by the maple is reduced to 1d10.
Starter Setup for Mechanical Traps:
And given I wanted to cover the sorts of traps you'd see on the planes, I've added some traps made up of natural phenomena that are more likely on the planes. The falling boulder also works with rules for which effects/spells/ect. work differently on various elemental planes. These feel like the weakest of the bunch, partially because some of them are flexible in the areas they over and the damage they deal (so the point of preparing a write out is minimal) and some of the others are trying to represent an actual danger of mining within the framework of 5e where the PCs are expected several chances. I like that they're expected several chances, because an instant failure on one bad roll isn't very interesting, the two competing factors just make verisimilitude a lot harder to gel the two together.
Simple trap (level 5-10, dangerous threat)
On the plane of air, there is no lower surface to the plane. Objects fall in reference to where the local creatures think of as down, often leaving large boulders hurling in strange directions. A random boulder flying by can be deadly, especially if it sends another creature hurling off into the void. While the inherent traits of plane of air slow falling speeds, being hit with a large object hurts, even on moving relatively slowly.
Trigger. A creature or vessel steps, flies, or floats less than 60 feet in front of the boulder’s path.
Effect. The target must make a DC 15 Dexterity saving throw. On a failed save the target takes 4d6 bludgeoning damage and is knocked 60 feet along the boulder’s path. On a success the target takes half as much damage and isn’t knocked away by the boulder.
Countermeasures. Effects which would slow the boulder’s fall stop it dead in its tracks for the duration.Intermediate trap (level 5-10, dangerous threat)
Collapsing passages are a constant risk in any sort of mine, but the plane of earth shifts faster than in the underdark or along surface mines, making them more common there.
Trigger. A spell’s area intersects with the wall or a weapon attack hits the weak section of wall, dealing at least 10 points of acid, bludgeoning, or thunder damage.
Effects. The ceiling collapses from the point where the passage was struck in a cylinder with a 20 foot radius and a height equal to the room. Each creature within the space must make a DC 20 Dexterity saving throw. On a failed save the target takes 8d6 bludgeoning damage and is restrained by the rubble. On a success the target takes half as much damage and can expend movement up to its movement speed to escape the area of the collapse.
Countermeasures. A creature can identify the wall’s weakness with a successful DC 20 Intelligence check. Dwarves can add their proficiency bonus to this check. The wall can be supported with a wooden or other physical support or reinforced with the stone shape spell.Complex trap (level 5-10, deadly threat)
The term for potentially explosive gasses released while mining, firedamp is the reason many creatures avoid using flame underground. Afterdamp, the name for the dangerous mix of gasses produced after firedamp burns out, is not any less dangerous.
Trigger. Firedamp and Afterdamp both have harmful effects when inhaled, and firedamp is explosive.
Inhalation. A creature spending 1 round inside the area of firedamp or 1 minute in the area of afterdamp triggers the effect. Creatures of tiny size instead trigger the effects of afterdamp every other round. A creature triggering these damps must make a DC 20 Constitution saving throw, with effects as detailed below.
Explosion. Firedamp is triggered when exposed to an open flame. An enclosed flame, such as that of lamp, hisses as spits sparks for 1 round before detonating on the same initiatve count as when it entered the firedamp’s area.
Effect. Firedamp and afterdamp have very different effects, one being a flamable gas and the other the improperly burnt remains of an explosion.
Firedamp Inhalation. On a failed saving throw made against firedamp, a creature falls prone. Once a creature has failed three saving throws against firedamp, it becomes unconscious as well. An unconscious creature automatically fails its saving throw against firedamp and gains one level of exhaustion each time it fails the saving throw. Track the total number of saving throws: a failed saving throw is only negated when the creature spends a full round breathing clean air.
Firedamp Explosion. When exposed to flame, the area of firedamp explodes, and each creature within the firedamp’s area must make a Dexterity saving throw, taking 8d6 fire damage on a failed save or half as much on a success. The area of firedamp then turns to afterdamp.
Afterdamp. On a failed save against afterdamp, the creature has disadvantage on ability checks for 1d4+1 hours. If a creature already subject to this effect fails this saving throw, it instead gains one level of exhaustion.
Countermeasures. A creature which has seen firedamp’s effects, either to a creature or when exploding, can identify it with a successful DC 15 Survival (Wisdom) check. If the creature suceeds on the check by 5 or more, it also recalls the effects and existance of afterdamp.
Clearing Damp. Firedamp and afterdamp are both cleared by proper ventilation, which can be forced out by wind of at least moderate speed (at 10 miles per hour) as long as it has somewhere to go. Poorly ventilated, areas without space above them will refill with firedamp if a pocket of it opens into the passage, unless prevented from accumulating by air funneled into the cave system to keep it clear.
Healing Firedamp. Creatures knocked uncconscious by afterdamp recover one level of exhaustion each minute they spend in clear, breathable air, to a minimum of the levels of exhuastion caused by other sources, and wake up after 1d4 * 10 minutes.
A creature which has not been knocked unconscious by firedamp negates one failed saving throw against afterdamp for each round it spends in clean, breathable air.
Healing Afterdamp. Creatures exposed to afterdamp recover levels of exhaustion as normal, provided they have access to clean air.Intermediate trap (level 5-10, dangerous threat)
Blackdamp forms as part of the natural process of breathing and burning materials. On the surface it thins in the wide open spaces and is absorbed by plants, but can reach dangerous concentrations in cramped and dark caves. Creatures have resistance to effects which create fire while in the area of blackdamp, but not to temperatures high enough to deal fire damage.
Trigger. A creature spends 1 minute inside the blackdamp.
Effect. A creature first exposed to blackdamp must make a DC 15 Constitution saving throw. On a failed save the creature has disadvantage on ability checks for 1d4+1 hours. If a creature already subject to this effect fails this saving throw, it instead gains one level of exhaustion.
Countermeasures. A creature which has seen blackdamp’s effects, either to a creature or a flame, can identify it with a successful DC 15 Survival (Wisdom) check.
Clearing Blackdamp. Blackdamp is cleared by proper ventilation, forced out by wind of at least moderate speed (at 10 miles per hour) as long as it has somewhere to go. Poorly ventilated, low lying areas where blackdamp accumulates will refill with blackdamp after 2d6+2 days of the cave being inhabited unless prevented by air funneled into the cave system to keep it clear.
Healing Blackdamp. Creatures exposed to blackdamp recover one level of exhaustion each minute they spend in clear, breathable air, to a minimum of the levels of exhaustion caused by other sources.Simple trap (level 5-10, dangerous threat)
The plane of fire’s flowing surface could be reasonably expected to prevent to formation of pockets of water or lava, but in fact this feature of the solid fire making up the plane readily separates fluids into small pockets, which tend to erupt readily at the surface as the surrounding fire sinks around it. Near the fountains of creation and through the cinder wastes geysers are most often found along gullys where lava previously seeped below the surface and is returning in larger pockets. Along the sea of fire, they most often appear along steeper hillsides collapsing into the sea.
Trigger. Some geysers erupt on a schedule, but most geysers erupt when a creature of sufficient weight disturbs the surface. A creature stepping on the geyser's space must succeed on a DC 10 Dexterity saving throw or trigger the geyser. A creature that lands prone in the geyser's space has disadvantage on this saving throw.
Effects. The geyser erupts in a 15 foot vertical cone pointing straight upward. Each creature in the line must make a DC 15 Constitution saving throw. On a failed save the creature is pushed 5 feet from the geyser's space in a random direction, be knocked prone, takes 11 (2d10) bludgeoning damage, and 11 (2d10) fire damage. On a success the creature takes half as much damage, isn’t knocked prone, and is pushed 5 feet in a direction of its choice.
Countermeasures. A DC 15 Perception (Wisdom) check allows a creature to identify the slightly raised space showing where a geyser is about to breach the surface. A creature using a tool at least 10 feet long can make a DC 15 Strength check to release the geyser from outside its area of effect. The geyser can also be safely triggered with any effect which churns the earth in the geyser's space enough to turn it to rough terrain.Intermediate trap (level 5-10, deadly threat)
Portals connecting the planes of fire and magma to the plane of water are often underground, resulting in boiling hot vents which eject nutrients into the surrounding water. Found at higher elevations on the plane of water than in oceans on the material plane, swimming to close too one can cook you alive in a matter of moments.
Trigger. A creature passes within the column of superheated water being emited from the black smoker. This column is emited in a 400 foot, 5 foot wide cylinder from the mouth of the black smoker. The cylinder is filled with dense soot, created by the mixture of elemental fire and water at the planar portal which which the smoker originates
Effects. A creature which enters into the smoker’s column or ends its turn there must make a DC 20 Constitution saving throw. On a failed save the creature takes 8d6 fire damage and is blinded for 1 minute. On a success the creature takes half as much damage and isn’t blinded. The initial damage is reduced by 1d6 for every 50 feet it is from the smoker’s mouth.
A creature blinded by the smoker can repeat the saving throw at the end of each of its turns, ending the effect on a success.
I had a thread for a bunch of plant based traps for the outer planes, and here I've made some for the inner planes as well. Given there's a slightly greater focus on explaining how these plants survive on the inner planes in the first place, I don't think the traps turned out quite as interesting, but at least these give some additional interest to the planes. Please note these traps are based on the elemental planes as presented in the 5e DMG, which breaks the main four elemental planes into separate regions.
Cash Crops:
With two on the plane of fire and two on the plane of air, I expect there to be a very different culture regarding the two. The Djinn are chaotic good, meaning they likely have individualized groves or gardens of these plants. The Chaotic Evil Efreet, in contrast, probably run brutal plantations to harvest larger quantities of the plant. You could maybe have an adventure around that, where a good aligned elemental needs medicine, but also wants it ethically sourced.
Intermediate trap (level 5-10, deadly threat)
The sap of myrrh trees is thick and quickly forms thick, chunky sap when exposed to air, much like blood clotting. The floating myrrh trees native to the plane of air produce distinctly stronger and more pungent sap, which is difficult to collect on account of the vicious spikes covering the tree’s surface, and the dificulty of holding still to collect the sap on the ever shifting plane.
Trigger. The thorns are triggered when creatures flies, is blown, or falls into the tree’s space, or the tree falls into a creature. The sap is triggered when the tree takes at least 5 points of slashing or acid damage as well as when it is burned.
Effects. The spines of the tree pierce deep into passing creatures, and the sap inflicts a pleasant state while harming the vectors of disease.
Thorns. A creature which interacts with the thorns must make a DC 15 Dexterity saving throw, taking 4d6 piercing damage on a failed save or half as much on a success. a creature attempting to grab onto the tree has disadvantage on the saving throw, while one attempting to climb the tree once it has attached itself has advantage on the saving throw.
Sap. The sap of the floating myrrh tree has medicinal properties, but is harmful when fresh or in high doses. When taking more than 4 doses in a 24 hour period a creature must make a DC 20 Constitution saving throw. On a failed save the creature takes 4d4 poison damage and has disadvantage on Constitution checks and saving throws for 24 hours. On a success the creature takes half as much damage and has disadvantage on Constitution checks for 8 hours instead. When a cut strong enough to trigger the tree is made, each creature within 5 feet of the cut must make the same saving throw, after which 2d4 pieces of myrrh can be harvested from the cut.
Prepared Compounds. Breathing in myrrh smoke for at least 1 minute grants you advantage on your next saving throw against any poison or disease affecting you.
When applied to a creature that has lost hit points within the last minute, myrrh causes the creature to heal 1d6 hit points, up a maximum of the number of hit points it lost in that period. The creature then cannot benefit from myrrh in this manner for 1 minute or until it takes damage. Applying the myrrh requires a successful DC 10 medicine check.
If a creature ingests 5 pieces of myrrh over a short or long rest, it must make a saving throw as described in the sap section, but all poisons ingested by the creature end at the end of the rest.
Myrrh from mundane plants on the material plane typically sell for 25 gold per pound. Myrrh from the floating myrrh trees of the plane of air are much more potent and typically yields a price of 25 gp per piece.
Countermeasures. A creature can notice the sharp spines of the floating myrrh tree with a successful DC 5 Perception (Wisdom) check, and identify it as a myrrh tree with a successful DC 10 Nature (Intelligence) check.
The tree has an AC and saving throws equivalent to those of an Awakened Tree, although it is an inanimate, nonmagical plant.Simple trap (level 1-4, moderate threat)
A flower whose large stamens produce a pleasant tingling sensation and a give food a light blue color when mixed in, static saffron is the most valuable export produced on the plane of air. It is most often pollinated by sky bees, which are also native to the plane and immune to lighting damage. With blooms a foot across they are often kept for decoration and honey production even if not used to collect spice. The plane’s djinn prefer servants to forced labor, but still push for production from shockers and others able to safely harvest the stamens. Unlike true saffron, the plants are capable for producing seeds, but the spice is collected from the portion of the flower responsible for starting this process rather than one one which produces pollen.
Trigger. A creature attempts to pick the three inch long stamens from a static saffron flower.
Effect. The creature must make a DC 10 Constitution saving throw, taking 1d10 lightning damage on a failure or half as much on a success.
Blooming year round, a 10 foot patch of static saffron contains 4d4 flowers at any given time. 10 flowers produce enough for 1 fluid ounce of static saffron, which sells for 100 gp.
Countermeasures. A successful DC 10 Survival (Wisdom) check allows a creature to identify the stamens of the flower as edible. If a creature succeeds on the check by 10 or more, or succeeds on a DC Investigation (Intelligence) check studying insects on the flower identifies the stamens electrocute when disturbed.Simple trap (level 5-10, dangerous threat)
The blooms of radiant poppies release dangerous amounts of harmful light, which withers and scorches even creatures immune to extreme heat. Grown for their narcotic sap radiant poppies are fully effective for elementals otherwise immune to poison. A creature can spend 1 minute harvesting immature seed pods from a 5 foot square of poppies, collecting 50 gp worth of sap from the square if the poppies are in full bloom or half as much from one finished blooming.
Trigger. A radiant poppy’s blooms affect any creature within 5 feet of a patch of radiant poppies in bloom.
Effects. Radiant poppies inherently harm nearby life, but are grown for their effects on elementals and other creatures.
Blooms. A creature which enters or starts its turn in a 5 foot square of blooming radiant poppies must make a DC 15 Constitution saving throw, taking 1d4 radiant damage on a failed save or half as much on a success.
Prepared Compounds. A creature can prepare 1 dose of knockout draught from 50 gp worth of radiant poppy sap and 25 gp worth of additional materials, subject to the normal crafting rules. One draught sells for 150 gp. A creature that ingests this compound must make a DC 15 Constitution saving throw or fall unconscious for 1 minute, until the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake. Elementals cannot benefit to immunity to poison against this effect.
Countermeasures. A creature can identify there is something off about the poppy’s space with a successful DC 5 Perception (Wisdom) check, and identify radiant poppies with a successful DC 15 Nature (Intelligence) check.
Destroying the Patch. Radiant poppies are immune to fire, piercing, psychic, and radiant damage and has vulnerability to effects dealing damage to an area. A 5 foot square of poppies has 10 (4d4) hit points.Simple trap (level 5-10, deadly threat)
Where black pepper is spicy to ward off mammals from eating its seeds, white pepper seeks to avoid being messed with by fire elementals on the plane on which it grows. Still occasionally found wild on the plane white pepper is a delicacy and a prize export from the plane of fire. The plants resemble black pepper, but with much thicker vines and leaves, and peppercorns half an inch across. The Efreet are the largest producers of white pepper, having massive numbers of slaves to harvest and process it. A 10 foot square of white pepper plants produces about 50 peppercorns, which weigh 1 pound. White pepper is worth 300 gp per pound when processed, and half as much unprocessed.
Trigger. A creature cuts into a portion of the white pepper plant, including to harvest peppercorns, or bites into the peppercorn.
Effects. The cooling substances that allow white pepper to grow on the plane of fire erupt in frost when disturbed, and are packed into the peppercorns with a much greater density. When triggered, the triggering creature must make a DC 20 Constitution saving throw, as the air around the cut momentarily freezes solid. The triggering creature takes 8d10 cold damage on a failed save, or half as much on a success.
A creature which has proficiency with the herbalism kit gains a bonus to its saving throw equal to its proficiency bonus to its saving throw when harvesting peppercorns by hand.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify white pepper. A DC 10 Survival (Wisdom) or DC Perception (Wisdom) saving throw allows a creature to notice the relative cold in the plant’s space.
Limited Frost. Once triggered, a peppercorn’s frost is expended. A 5 foot portion of live plant regains the ability to deal cold damage at the site of cuts at the rate of 1d10 per hour, to a maximum of 8d10.
Other Flora:
Some of these are based on real plants (primarily on the plane of water) but the others fill some niche. For instance, the stonecatcher vine can form a location for a PC to land if they fall away from the party. It help that, the stonecatcher can catch the PC itself, making it harder for the PC to miss. Ironthorn, on the other hand, is a hassle to kill and was written to justify why the plane of earth can have a surface but the mines all still run underground for their full length.
Simple trap (level 5-10, moderate threat)
Mostly isolated to Mistral Reach, various epiphytes tossed into the plane over the centuries have adapted to the environment. Some float toward surfaces from which to gather moisture and nutrients, but the beating epiphyte bats away both potential grazers and other surfaces.
Trigger. A creature or object touches the epiphyte.
Effect. One of the epiphyte's stems lashes out at the target with a +4 to hit bonus. On a hit, the target takes 2d6 bludgeoning damage and must make a DC 10 Wisdom saving throw. On a failed save the target loses track of which way is down for 1 minute and start falling in a random direction. At the end of each of its turns the target can repeat the saving throw, ending the effect on a success.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the epiphyte’s stems are capable of motion. A stem can be severed with a successful weapon attack against an AC of 15, which must deal at least 5 points of acid, bludgeoning, or fire damage.Intermediate trap (level 1-4, deadly threat)
While the largest earthbound settlements on the plane of air are found on the largest motes of stone found, there also exist patches of smaller rocks bound together by stonecatcher vines, which grab onto passing falling objects in search of additional nutrients. Stonecatcher vines can form patches over a hundred feet across, providing habitat for various flying insects and small birds whose ancestors became trapped on the plane long ago.
Trigger. An object of small size or larger passes within 5 feet of the vine while moving at a speed of 60 feet per round.
Effect. The vine strikes out at the object. The vine has an attack modifier of +12. On a hit the vine deals 4d6 bludgeoning damage and the target is grappled by the vine. A medium or smaller target is restrained while grappled in this manner. If the target is huge or larger the grappling vine is severed from the main plant and remains grappling the target. In 1 hour the severed vine grows enough roots to bind it to a grappled object made of stone, wood, or flesh.
Countermeasures. A successful DC 10 Nature (Intelligence) check reveals the nature of the vine.
Escaping the Vine. A grappled creature can free itself from the vine with a successful DC 20 Acrobatics (Dexterity) check or Athletics (Strength) check.
Removing the Vine. A creature can dislodge a 5 foot section of grappling stonecatcher vine from the surface attached to it with a successful DC 20 Athletics (Strength) check. Removing the roots of a stonecatcher vine requires a DC 20 check with carpenter’s tools to remove each root; a 5 foot section of stonecatcher vine will have 2d4 roots holding it to the surface it grows on.Simple trap (level 5-10, deadly threat)
An unassuming bush only marked by the lack of other vegetation within 1 foot of its leaves, the alchemy plant produces sugar by converting nearby substances into the necessary component parts. It survives by transforming itself and neighboring objects into whatever it expects them to find inedible; attempts to bite the plant see it turn to worthless stone and attempts to cut it see it become steel.
Trigger. A creature touches the alchemy plant, an object touches the plant, or two inanimate objects touch the plant.
Effects. The alchemy plant reacts differently based on the number and types of objects touching it.
Flesh and Bone. When touched by living material, the alchemy plant turns to stone until the contact ends. If contact lasts more than a full round, the touching creature must make a DC 20 Dexterity saving throw. The limb of the creature that fails the save begins to turn to stone and a creature of tiny size is restrained. A target creature must repeat the saving throw at the end of its next turn, with its limb turning to stone and becoming unusable, or becoming petrified if it is a tiny creature.
One object. While in contact with one object, the alchemy plant turns to the same substance, turning to whichever material is being used to try to cut it, or stone if touched by the denizens of the plane.
Two objects. When a second object touches the alchemy plant, there is a 50% chance that either object is converted to the substance of the other over the course of the next round. The quantity of either object converted is of equal size to the smaller of the two objects.
Countermeasures. A creature can identify an alchemy plant with a successful DC 20 Nature (Intelligence) check.
Picking the Plant. The plant requires concentration to transmute its own form (as if Concentrating on a spell). A creature can uproot the alchemy plant with a successful DC 20 Strength check, killing the plant instantly. Objects and creatures being converted by the plant only cease to be transmuted if the plant is killed in the round during which they are transmuted.
Restoration. A creature restrained by the alchemy plant’s effect or a limb converted within the last round can be healed and the effect ended using the lesser restoration spell, the remove curse spell, or stronger magic. A fully petrified creature remains petrified until it is freed by the greater restoration spell or other magic which can end the condition.Intermediate trap (level 5-10, dangerous threat)
One the material plane, there are species across most major groups of fungi which prey on nematodes, some by snaring them in ring like growths, spread out to effectively catch prey struggling to escape. The relatives of these fungi on the plane of earth are massive, able to wrap themselves around creatures of even medium size to feed.
Trigger. A creature touches one of the fungus’s snares.
Effects. The fungus maintains methods to strengthen its grip on captured prey as it struggles.
Capture. The snare springs shut, and the target must make a DC 10 Dexterity saving throw or be restrained by the trap. A trapped creature can make a DC 10 Athletics (Strength) or Acrobatics (Dexterity) check to try to escape the trap. Additionally, a creature within 5 feet of the restrained creature can attempt a DC 10 Athletics (Strength) check, freeing the target on a success.
Escalation. When a creature fails on its check to free a creature from the fungus or to sever a snare, the creature triggers an additional snare within 5 feet of the first. A creature must escape each snare restraining it separately.
Quell. A creature which starts it turn restrained by the fungus takes 1d6 bludgeoning damage for each snare restraining it.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the fungal snare.
Killing the Fungus. A snare an be severed with a successful attack dealing at least 10 points of slashing or acid damage to the snare, which has an AC of 10. If targeted with a blight spell, a 10 foot patch of fungus is destroyed.Simple trap (level 5-10, dangerous threat)
Growing in thin, vertical spikes on the plane of earth, ironthorn plants can grow up to 3 feet straight up, absorb massive amounts of iron from the surrounding environment with their wide roots, making the plants incredibly resistant to grazing. Patches established on top of iron deposits on the material plane often prove difficult to remove. Thankfully, the surface of the plane of earth is one of the few places with enough iron to sustain a population of ironthorn of any significant size. Unfortunately, digging even a few feet through ironthorn plants can prove harder than mining iron elsewhere.
Trigger. The ironthorn is dangerous to enter, and more dangerous to try digging through.
Trampling. A creature steps into the ironthorn’s space.
Digging. A creature attempts to sever the stem or roots if the ironthorn, such as by attacking it.
Effect. The edges and blades of the ironthorn are razor sharp, and the wiry plant resists attempts to sever it to an extreme extent.
Trampling. The triggering creature must make a DC 15 Dexterity saving throw. On a failed save the creature takes 4d8 piercing damage and 2d8 slashing damage. The creature takes half as much damage on a success.
Digging. The triggering creature must make the saving throw as against trampling the ironthorn. If using a nonmagical weapon or tool the item takes 3d6 damage, ignoring its AC.
Countermeasures. A creature can identify ironthorn with a successful DC 15 Nature (Intelligence) check. A creature can identify the plant is extremely sharp with a successful DC 5 Survival (Wisdom) check.
Destroying the Plant. A 5 foot patch of ironthorn has 150 hit points, immunity to lightning, piercing, and psychic damage and resistance to all other damage types except necrotic and slashing damage. It withers and dies instantly if targeted with the blight spell. Once killed the remaining dead roots have 100 hit points, immunity to lightning, necrotic, piercing, poison, and psychic damage, and resistance to all other damage types except slashing damage.Intermediate trap (level 5-10, dangerous threat)
Plants resembling massive pitchers, cauldron plants desperately try to grab and digest any trace of water they can find on the plane of fire where they grow.
Trigger. A creature walks within 5 feet of the cauldron plant.
Effects. The plant attacks with a +5 bonus to the attack roll. On a hit the plant deals 11 (2d10) piercing damage and grapples the target. Until this grapple ends the plant can’t attack another target.
A creature can make a DC 15 Strength (Athletics) check, freeing itself from the plant and ending the condition on a success. A creature can also make this check to free another creature within reach of the cauldron plant.
Swallow (Initiative 10). The plant attacks with a +5 bonus to the attack roll. On a hit the target takes 11 (2d10) piercing damage, 10 (4d4) acid damage, and becomes restrained by the cauldron plant.
Dissolve (Initiative 10). A creature that starts its turn restrained by the cauldron plant takes 20 (8d4) acid damage.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify a cauldron plant.
Attacks. The cauldron plant has an AC of 8. Each attack dealing at least 5 points of slashing damage to the cauldron plant reduces the plant’s attack bonus and the DC to escape the plant by 2. The plant’s pot becomes too shredded to grapple if its attack bonus is reduced to +0.Simple trap (level 5-10, moderate threat)
Marked by its 10 foot tall bundle of leaves and the smaller plants growing around its base, the static burster unleashes bolts of lightning at creatures which move past, its foot long ashen leaves turning bright amber as it does so.
Trigger. A creature of small size or larger passes within 10 feet of the static burster’s base or an object weighing 20 pounds or larger strikes the plant or the ground within 10 feet.
Effects. The plant unleashes a blast of lightning in a 1 foot wide, 20 foot long arc of lighting in the direction of the triggering creature or object. Each creature in the line’s space must succeed on a DC 15 Dexterity saving throw or take 21 (6d6) lightning damage. A full grown static burster has 2d6+3 leaves, each growing 10 feet tall in the plant’s space.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify a static burster.
Discharge. Each leaf of the plant can hold up to one charge, and turns bright amber when it discharges lightning. Once discharged, the leaf rebuilds this charge by 1d6 each hour, turning fully ashen when it reaches a full charge of 6d6 lightning damage.
Severing. Each of the leave’s stems has 5 (2d4) hit points, and immunity to fire, lightning, piercing, and psychic damage. It can also be torn off with a DC 20 Athletics (Strength) check. A severed leaf’s maximum charge is reduced to 10 (3d6) lightning damage, which it discharges when it hits the ground or is touched by a creature. A severed leaf can’t regain charge.Intermediate trap (level 5-10, dangerous threat)
Growing in the endless flowing surface of the plane of ooze, clambering mangroves wrap their roots around whatever solid objects they encounter, staying above the muck by grabbing wreckage, wood, and creatures and pushing them below itself.
Trigger. A creature or object knocks against the mangrove’s roots.
Effects. A triggering object is grappled by the mangrove. A triggering creature must make a DC 15 Acrobatics (Dexterity) or Athletics (Strength) check (its choice). On a failed check the creature is restrained by the mangrove. A grappled creature can repeat the check, escaping the tree on a success. A creature can attempt a DC 15 Athletics (Strength) check to free a grappled target, but must avoid being grappled by the mangrove before it can attempt the check.
A creature that starts its turn grappled by the mangrove must make a DC 15 Constitution saving throw, taking 4d6 bludgeoning damage on a failed save. A creature knocked unconscious is pushed underwater, where it risks drowning.
Countermeasures. A DC 15 Nature (Intelligence) check allows a creature to identify the tree. A mangrove’s root can be severed by dealing at least 10 points of slashing or acid damage to it with a single attack action.Simple trap (level 5-10, moderate threat)
Snapweed is named for the eruption of the seed pods, which can extend multiple feet in the varieties found on the prime material. Instant snapweed, native to the plane of ooze, grows to full height and flings its seeds almost as quickly, with enough force to send many creatures fleeing for safety.
Trigger. Any creature that enters the area of instant snapweed seeds must succeed on a DC 15 Dexterity saving throw or trigger the trap.
Effects. For 1 round after being triggered, the snapweed grows to 3 feet in height. On initiative count 10 of the next round, the snapweed bursts, flinging seeds in a 20 foot long cone in the direction of the triggering creature. The ground below the cone becomes covered in instant snapweed seeds, which become mature enough to be triggered after soaking in water for 24 hours.
Each creature in the cone’s space must make a DC 10 Dexterity saving throw, taking 2d6 bludgeoning damage on a failed save or half as much on a success.
Countermeasures. A DC 20 Nature (Intelligence) check allows a creature to identify the seeds of instant snapweed, and a DC 10 Nature (Intelligence) check allows a creature to identify instant snapweed while it is growing.
Instant snapweed seeds are killed if subject to an area which deals fire or cold damage. A creature can spend 1 minute clearing a 5 foot square of snapweed seeds. If the seeds are mature the creature must make a saving throw to avoid triggering a trap.Simple trap (level 1-4, dangerous threat)
Sometimes nicknamed the “little apple of death,” manchineel trees contain highly toxic sap throughout, even on the fruit, potent enough to blister the skin if rain washes it onto you. A number of these plants survive on islets on the plane of water, preventing habitation where they grow.
Trigger. A creature makes a melee attack targeting the tree, stands under the tree in the rain, or stands within smoke from fresh Manchineel wood.
Effects. The triggering creature must make a DC 15 Constitution saving throw. On a failed save the creature takes 2d4 acid damage and is blinded for 1 minute. On a success the creature takes half as much damage and isn’t blinded.
Countermeasures. A DC 10 Nature (Intelligence) check allows a creature to identify the tree. If burnt at the base the tree can be felled, after which the sap takes 1 week to dry. Once dried the wood can be used safely.Simple trap (level 5-10, moderate threat)
Of the threats found in the sea, red tide may be one of the most insidious. Born from massive swells in the populations of local algae, which often produce toxins and drain the oxygen from the water. The most common variety of red tide found on the plane of water is highly toxic, killing wide swaths of native marine life when it takes over the area.
Trigger. The effects of red tide become more severe the longer a creature spends time in it.
Inhalation. A creature enters the area of the red tide or the tide drifts into the creature’s space. A creature which does not need to breath or which has protection from inhaling the surrounding water does not trigger the red tide.
Extended Inhalation. For every 2 hours a creature spends in contact with red tide in a 24 hour period, it must make an additional DC 5 Constitution saving throw.
Effects. On each turn, on initiative count 0 the tide flows with the current, typically 10 feet per round.
Inhalation. When a creature enter’s the area of the red tide it must make a DC 5 Constitution saving throw. On a failed save, the target has disadvantage on Constitution saving throws against inhaled poisons, diseases, and gasses for 2d4+2 hours.
Extended Inhalation. When a creature fails its subsequent saving throw against red tide, it becomes poisoned for 24 hours. If the creature was already poisoned in this manner, it instead gains 1 level of exhaustion.
Countermeasures. Red Tide an be identified with a successful DC 10 Nature (Intelligence) check. Creatures which don’t breath or which avoid breathing in the water afflicted with red tide do not trigger it. Unfortunately, killing red tide fails to remove or purify the area of the toxins.
Self Protection. The amount of poison produced by red tide is minimal, and granting a creature advantage on saving throws against the tide can greatly extend how long a creature can travel through it. Many creatures living on the plane of water also accumulate items which help produce water or control its flow, allowing them beat away sections of red tide and create clean water to breathe.
Elemental Phenomena Looking Like Plants:
The lore of elementals take the form of animals is older, so I figured there should be elemental entities which also resemble plants.
Simple trap (level 5-10, dangerous threat)
Vertical icicles bearing masses of sharp frost, creatures standing beneath so-called “frost pines” are in danger of being sprayed by shards of ice while standing beneath them. They grow in groves on the plane of ice, but where the vegetation in taiga provides cover and nutrients, passing inside frost pines only risks being struck with a hail of needles. For reasons still debated by scholars, frost pines reach a uniform height of 30 feet tall.
Trigger. A creature or object strikes the icicle dealing damage other than fire, poison, or psychic damage, or an effect which moves either the surface beneath the pine or the pine itself.
Effect. The area in a 10 foot wide, 30 foot tall cylinder originating from the top of the pine explodes with thousands of tiny needles. Creaures in the cylinder’s space must make a DC 15 Dexterity saving throw. On a failed save each creature takes 3d6 piercing damage and 1d6 cold damage. On a success the target takes half as much damage.
Countermeasures. A triggered frost pine takes 4 hours to regrow its needles, during which the size of the eruption is reduced. After 1 hour the pine deals 1d6 cold damage when triggered, and deals 1d6 additional piercing damage for each additional hour it is left to grow.
Fire Damage. If an area of the icicle takes fire damage, the icicles in that area melt and reduce the damage dealt by the tree by 1d6 for every 5 points of damage. The pine has vulnerability to fire.Simple trap (level 5-10, moderate threat)
Native to the plane of fire, choking willows grow on the banks of lava flows on their way from the fountains of creation to the sea of fire. The branches bend down over the streams they grow from, their small leaves smoking slightly. When disturbed by the wind or shaken, the trees release bursts of smoke, warding off creatures and sending pollen floating on the breeze.
Trigger. The tree is exposed to moderate wind (10 miles per hour or higher) or shaken be the creature.
Effects. The tree emits dense smoke in a 15-foot-radius, 30-foot-high cylinder around the tree. The smoke spreads around corners, and its area is heavily obscured. It lasts for 10 minutes or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.
Each creature that starts its turn or enters the smoke during its turn must make a DC 10 Constitution saving throw. On a failed save the target gains one level of exhaustion and is blinded for 10 minutes.
Countermeasures. A DC 15 Nature (Intelligence) check allows a creature to identify the tree. Once a tree has been triggered, it won’t release smoke again for 1 hour. An area of effect dealing acid or lightning damage prevents the tree from emitting smoke in the area the two effects would overlap, taking the tree 1 week to regrow.Simple trap (level 5-10, moderate threat)
Jets of fresh water naturally form on the plane of water, not only spraying up from the surface on the water, but also where water of different salinities meets in the darkened depths. Nicknamed sweetwater maples on account of their treelike shape and how they can be tapped for fresh water, they are a critical resource for surface dwellers crossing the plane. Groups of these waterspouts, referred to as groves, are important resources on the plane, and the largest and finest groves produce large quantities of pure water, which sells for as much as wine due to its resistance to spoiling. Different groves produce water with slightly different taste, and some marids run wateries with produce selling up to 15 gp per bottle. Unlike wine, aging sweetwater maple “sap” has no effect.
Trigger. The vortex of the maple produces a constant cone of rushing water, pointed straight up, stemming from a central trunk up to 5 feet wide and 10 feet tall. A creature triggers the maple when passing through the canopy or first inserts a spout into the trunk, which look much like the taps drilled into maple trees.
Effect. The triggering creature must make a DC 10 Strength saving throw, taking 2d10 bludgeoning damage on a failed save or half as much on a success. If a creature attempting to insert a tap fails the saving throw, it also fails to insert the tap.
Countermeasures. A creature can identify sweetwater maples as a source of clean drinking water with a successful DC 15 Survival (Wisdom) check. A creature has advantage on this check if it has tasted the spray from maple.
Controlling Water. Effects which control water can slow a sweetwater maple’s flow. Instantaneous effects, such as the shape water spell, can slow the jet for 1 round, and lasting effects, such as the control water spell affect the jet for the duration. While the rate of flow is slowed the damage dealt by the maple is reduced to 1d10.
Starter Setup for Mechanical Traps:
And given I wanted to cover the sorts of traps you'd see on the planes, I've added some traps made up of natural phenomena that are more likely on the planes. The falling boulder also works with rules for which effects/spells/ect. work differently on various elemental planes. These feel like the weakest of the bunch, partially because some of them are flexible in the areas they over and the damage they deal (so the point of preparing a write out is minimal) and some of the others are trying to represent an actual danger of mining within the framework of 5e where the PCs are expected several chances. I like that they're expected several chances, because an instant failure on one bad roll isn't very interesting, the two competing factors just make verisimilitude a lot harder to gel the two together.
Simple trap (level 5-10, dangerous threat)
On the plane of air, there is no lower surface to the plane. Objects fall in reference to where the local creatures think of as down, often leaving large boulders hurling in strange directions. A random boulder flying by can be deadly, especially if it sends another creature hurling off into the void. While the inherent traits of plane of air slow falling speeds, being hit with a large object hurts, even on moving relatively slowly.
Trigger. A creature or vessel steps, flies, or floats less than 60 feet in front of the boulder’s path.
Effect. The target must make a DC 15 Dexterity saving throw. On a failed save the target takes 4d6 bludgeoning damage and is knocked 60 feet along the boulder’s path. On a success the target takes half as much damage and isn’t knocked away by the boulder.
Countermeasures. Effects which would slow the boulder’s fall stop it dead in its tracks for the duration.Intermediate trap (level 5-10, dangerous threat)
Collapsing passages are a constant risk in any sort of mine, but the plane of earth shifts faster than in the underdark or along surface mines, making them more common there.
Trigger. A spell’s area intersects with the wall or a weapon attack hits the weak section of wall, dealing at least 10 points of acid, bludgeoning, or thunder damage.
Effects. The ceiling collapses from the point where the passage was struck in a cylinder with a 20 foot radius and a height equal to the room. Each creature within the space must make a DC 20 Dexterity saving throw. On a failed save the target takes 8d6 bludgeoning damage and is restrained by the rubble. On a success the target takes half as much damage and can expend movement up to its movement speed to escape the area of the collapse.
Countermeasures. A creature can identify the wall’s weakness with a successful DC 20 Intelligence check. Dwarves can add their proficiency bonus to this check. The wall can be supported with a wooden or other physical support or reinforced with the stone shape spell.Complex trap (level 5-10, deadly threat)
The term for potentially explosive gasses released while mining, firedamp is the reason many creatures avoid using flame underground. Afterdamp, the name for the dangerous mix of gasses produced after firedamp burns out, is not any less dangerous.
Trigger. Firedamp and Afterdamp both have harmful effects when inhaled, and firedamp is explosive.
Inhalation. A creature spending 1 round inside the area of firedamp or 1 minute in the area of afterdamp triggers the effect. Creatures of tiny size instead trigger the effects of afterdamp every other round. A creature triggering these damps must make a DC 20 Constitution saving throw, with effects as detailed below.
Explosion. Firedamp is triggered when exposed to an open flame. An enclosed flame, such as that of lamp, hisses as spits sparks for 1 round before detonating on the same initiatve count as when it entered the firedamp’s area.
Effect. Firedamp and afterdamp have very different effects, one being a flamable gas and the other the improperly burnt remains of an explosion.
Firedamp Inhalation. On a failed saving throw made against firedamp, a creature falls prone. Once a creature has failed three saving throws against firedamp, it becomes unconscious as well. An unconscious creature automatically fails its saving throw against firedamp and gains one level of exhaustion each time it fails the saving throw. Track the total number of saving throws: a failed saving throw is only negated when the creature spends a full round breathing clean air.
Firedamp Explosion. When exposed to flame, the area of firedamp explodes, and each creature within the firedamp’s area must make a Dexterity saving throw, taking 8d6 fire damage on a failed save or half as much on a success. The area of firedamp then turns to afterdamp.
Afterdamp. On a failed save against afterdamp, the creature has disadvantage on ability checks for 1d4+1 hours. If a creature already subject to this effect fails this saving throw, it instead gains one level of exhaustion.
Countermeasures. A creature which has seen firedamp’s effects, either to a creature or when exploding, can identify it with a successful DC 15 Survival (Wisdom) check. If the creature suceeds on the check by 5 or more, it also recalls the effects and existance of afterdamp.
Clearing Damp. Firedamp and afterdamp are both cleared by proper ventilation, which can be forced out by wind of at least moderate speed (at 10 miles per hour) as long as it has somewhere to go. Poorly ventilated, areas without space above them will refill with firedamp if a pocket of it opens into the passage, unless prevented from accumulating by air funneled into the cave system to keep it clear.
Healing Firedamp. Creatures knocked uncconscious by afterdamp recover one level of exhaustion each minute they spend in clear, breathable air, to a minimum of the levels of exhuastion caused by other sources, and wake up after 1d4 * 10 minutes.
A creature which has not been knocked unconscious by firedamp negates one failed saving throw against afterdamp for each round it spends in clean, breathable air.
Healing Afterdamp. Creatures exposed to afterdamp recover levels of exhaustion as normal, provided they have access to clean air.Intermediate trap (level 5-10, dangerous threat)
Blackdamp forms as part of the natural process of breathing and burning materials. On the surface it thins in the wide open spaces and is absorbed by plants, but can reach dangerous concentrations in cramped and dark caves. Creatures have resistance to effects which create fire while in the area of blackdamp, but not to temperatures high enough to deal fire damage.
Trigger. A creature spends 1 minute inside the blackdamp.
Effect. A creature first exposed to blackdamp must make a DC 15 Constitution saving throw. On a failed save the creature has disadvantage on ability checks for 1d4+1 hours. If a creature already subject to this effect fails this saving throw, it instead gains one level of exhaustion.
Countermeasures. A creature which has seen blackdamp’s effects, either to a creature or a flame, can identify it with a successful DC 15 Survival (Wisdom) check.
Clearing Blackdamp. Blackdamp is cleared by proper ventilation, forced out by wind of at least moderate speed (at 10 miles per hour) as long as it has somewhere to go. Poorly ventilated, low lying areas where blackdamp accumulates will refill with blackdamp after 2d6+2 days of the cave being inhabited unless prevented by air funneled into the cave system to keep it clear.
Healing Blackdamp. Creatures exposed to blackdamp recover one level of exhaustion each minute they spend in clear, breathable air, to a minimum of the levels of exhaustion caused by other sources.Simple trap (level 5-10, dangerous threat)
The plane of fire’s flowing surface could be reasonably expected to prevent to formation of pockets of water or lava, but in fact this feature of the solid fire making up the plane readily separates fluids into small pockets, which tend to erupt readily at the surface as the surrounding fire sinks around it. Near the fountains of creation and through the cinder wastes geysers are most often found along gullys where lava previously seeped below the surface and is returning in larger pockets. Along the sea of fire, they most often appear along steeper hillsides collapsing into the sea.
Trigger. Some geysers erupt on a schedule, but most geysers erupt when a creature of sufficient weight disturbs the surface. A creature stepping on the geyser's space must succeed on a DC 10 Dexterity saving throw or trigger the geyser. A creature that lands prone in the geyser's space has disadvantage on this saving throw.
Effects. The geyser erupts in a 15 foot vertical cone pointing straight upward. Each creature in the line must make a DC 15 Constitution saving throw. On a failed save the creature is pushed 5 feet from the geyser's space in a random direction, be knocked prone, takes 11 (2d10) bludgeoning damage, and 11 (2d10) fire damage. On a success the creature takes half as much damage, isn’t knocked prone, and is pushed 5 feet in a direction of its choice.
Countermeasures. A DC 15 Perception (Wisdom) check allows a creature to identify the slightly raised space showing where a geyser is about to breach the surface. A creature using a tool at least 10 feet long can make a DC 15 Strength check to release the geyser from outside its area of effect. The geyser can also be safely triggered with any effect which churns the earth in the geyser's space enough to turn it to rough terrain.Intermediate trap (level 5-10, deadly threat)
Portals connecting the planes of fire and magma to the plane of water are often underground, resulting in boiling hot vents which eject nutrients into the surrounding water. Found at higher elevations on the plane of water than in oceans on the material plane, swimming to close too one can cook you alive in a matter of moments.
Trigger. A creature passes within the column of superheated water being emited from the black smoker. This column is emited in a 400 foot, 5 foot wide cylinder from the mouth of the black smoker. The cylinder is filled with dense soot, created by the mixture of elemental fire and water at the planar portal which which the smoker originates
Effects. A creature which enters into the smoker’s column or ends its turn there must make a DC 20 Constitution saving throw. On a failed save the creature takes 8d6 fire damage and is blinded for 1 minute. On a success the creature takes half as much damage and isn’t blinded. The initial damage is reduced by 1d6 for every 50 feet it is from the smoker’s mouth.
A creature blinded by the smoker can repeat the saving throw at the end of each of its turns, ending the effect on a success.