Help with a custom spell I'm working on for a magic item

[Phoenix042]

So basically there's this magic scepter I'm designing called the Hellfire Scepter, and it's got a number of features. One of them is that it allows the wielder to cast the following homebrew spell using a 6th level slot, a maximum of once per day and at the cost of a level of exhaustion.

I'd like input on the spell's balance for a 6th level blasting / control spell, feedback on the clarity of the text, and opinions on the word choice and flavor text of the spell.

Basically, I want your opinion on every part of it.


Here's the spell:

Infernal Maw
6th level conjuration

Casting Time: 1 action
Range: 200ft.
Components: V, S, M (A bit of volcanic glass and a fire agate worth at least 1000gp)
Duration: Concentration, up to 1 minute

The earth comes alive with fiery malice, heaving and breaking in an area you choose within range. The ground splits and cracks, venting jets of flame and threatening to swallow any creature standing on it. The area this spell affects consists of up to four 20ft squares on the ground, which you can arrange as you wish.
The ground in this area becomes shot through with fiery fissures, 20ft deep and constantly shifting, alive with malice and hunger. For the duration, these fissures turn the ground in the area into difficult terrain.
When a creature enters the affected area for the first time on a turn or starts its turn there, the creature must succeed on a dexterity saving throw against your spell save DC or be swallowed whole by a fissure. A creature that falls into a fissure takes 3d6 fire damage, as well as bludgeoning damage appropriate to the fall (usually 2d6). A creature that starts its turn inside of a fissure instead takes 3d6 fire damage (no save).
A creature attempting to climb out of a fissure must succeed on a strength (athletics) check against your spell save DC or make no progress that turn. A creature that fails this check by 5 or more falls.
If you concentrate for the full duration of the spell, the fissures remain after the spell ends (though they no longer deal fire damage) and all standing structures in the area are completely destroyed.
At Higher Levels: When you cast this spell using a spell slot of 7th level or higher, the depth of the fissures increases by 10ft for each slot level above 6th.


The intent is that many creatures will have to use their action to dash in order to escape the fissures, and that some will need multiple turns to escape the fissures and the area of the spell when it is cast with slots higher than 6th level.

What do you all think?

[Breccia]

When comparing a multi-attack spell at 6th level, the obvious comparison is chain lightning, which is a flat-out 10d8 save for half. That's 45 damage between us statisticians.

For a creature to take 45 damage from this spell, they'd have to, for example, fail the first saving throw taking 5d6, then fail to escape three times. That's a lot of saves to fail. The spell's natural restrictions -- meaning that most flying and incorporeal creatures would ignore it, and creatures that climb naturally always take reduced damage -- which is okay. By contrast, a smart caster could do this:

https://i.imgur.com/dVuqTCL.jpg

and "wall" off even 15 foot reach enemies from getting to them.

My first read, the spell looks good, sacrificing knockdown power with defense and control in a way that doesn't seem to have an autowin. Everyone can try to climb 20 feet.

I do have some requests:

1) Limit the "all structures are destroyed" bit. 6th level spells are strong, not going to argue that, but there's got to be some kind of "structure takes 20d6" thing you could use instead? The spell you've created could be much more dangerous than the same level move earth, which doesn't have combat use at all. I'll admit, I don't know of any "structure AC and hit points" table, but a spell like this should flatten a house, but not bring down the entire dungeon they're standing in.

Or, just be a bit more clear about the rules to prevent using this spell to tunnel "four 20x20 squares that way". As someone who's personally destroyed an entire campaign by polymorphing into an umber hulk and tunneling through walls, I can tell you that it causes more problems than it solves.

2) Higher levels making the pits deeper, while yes a higher spell and therefore more "I'm done with you" power, gets closer to an "I win" effect, since climbing 30 feet in one round is not something everyone can do. Think about how your PCs would react if it hit them? Now, the spell does allow a save, or other escapes like flight or teleportation, so I won't cry myself to sleep if you leave this alone, but I personally would make it do more fire damage than falling just to let everyone have a chance to spend one single round to escape. I know it's part of your listed motive, and that's cool, it's just not the route I'd follow.

3) Allow the caster to make smaller squares. Some dungeons don't have rooms big enough to put this down safely.

[noob]

When comparing a multi-attack spell at 6th level, the obvious comparison is chain lightning, which is a flat-out 10d8 save for half. That's 45 damage between us statisticians.

For a creature to take 45 damage from this spell, they'd have to, for example, fail the first saving throw taking 5d6, then fail to escape three times. That's a lot of saves to fail. The spell's natural restrictions -- meaning that most flying and incorporeal creatures would ignore it, and creatures that climb naturally always take reduced damage -- which is okay. By contrast, a smart caster could do this:

https://i.imgur.com/dVuqTCL.jpg

and "wall" off even 15 foot reach enemies from getting to them.

My first read, the spell looks good, sacrificing knockdown power with defense and control in a way that doesn't seem to have an autowin. Everyone can try to climb 20 feet.

I do have some requests:

1) Limit the "all structures are destroyed" bit. 6th level spells are strong, not going to argue that, but there's got to be some kind of "structure takes 20d6" thing you could use instead? The spell you've created could be much more dangerous than the same level move earth, which doesn't have combat use at all. I'll admit, I don't know of any "structure AC and hit points" table, but a spell like this should flatten a house, but not bring down the entire dungeon they're standing in.

Or, just be a bit more clear about the rules to prevent using this spell to tunnel "four 20x20 squares that way". As someone who's personally destroyed an entire campaign by polymorphing into an umber hulk and tunneling through walls, I can tell you that it causes more problems than it solves.

2) Higher levels making the pits deeper, while yes a higher spell and therefore more "I'm done with you" power, gets closer to an "I win" effect, since climbing 30 feet in one round is not something everyone can do. Think about how your PCs would react if it hit them? Now, the spell does allow a save, or other escapes like flight or teleportation, so I won't cry myself to sleep if you leave this alone, but I personally would make it do more fire damage than falling just to let everyone have a chance to spend one single round to escape. I know it's part of your listed motive, and that's cool, it's just not the route I'd follow.

3) Allow the caster to make smaller squares. Some dungeons don't have rooms big enough to put this down safely.
Ironically destroying a small house by digging a pit can be harder than destroying a huge part of a deep dungeon for the simple reason that dungeons being often underground they frequently needs to hold the earth weight above them which makes them more vulnerable to structural damage and even if the dungeon is not underground the fact is that the force applied on a dungeon by a dangling part which is typically made of stone will be more intense than the force of a wooden section of a house.
But the objective is not to make physical sense but rather to make it not destroy the bbeg thingies too easily.
It would make sense to have that functionality if dnd 5e did want to keep the destroy everything easily option 3.5 had but dnd 5e does not.
In 3.5 disintegrate had a gigantic scaling area of effect against non creatures and there was really a lot of ways to destroy walls,floors and roofs going from hitting stuff with adamentine weapons to simply ramming them with your shoulder really hard or bashing an opponent in a wall at high speed repetitively(at least fighters did not lack ways to kill environment).

[Phoenix042]

For a creature to take 45 damage from this spell, they'd have to, for example, fail the first saving throw taking 5d6, then fail to escape three times. That's a lot of saves to fail.

I tried to be conservative on damage. I compared wall of fire, Evard's Black Tentacles, and basically every 6th level spell that deals damage. I decided to keep the damage in line with Black Tentacles but scaled up a little. Note that the damage each round after the first is low by that metric; it's no higher than Black Tentacles (two spell levels lower), but its also a worse type.

I'm concerned that (despite the obvious advantages of additional area) I might have made the spell a touch too weak in that regard.



The spell's natural restrictions -- meaning that most flying and incorporeal creatures would ignore it, and creatures that climb naturally always take reduced damage -- which is okay.

These restrictions are meant to be steep; lots of enemies have flying or climbing speeds. I will note, however, that the party that will be using this item has ways of knocking enemies prone at moderate range.



By contrast, a smart caster could... "wall" off even 15 foot reach enemies from getting to them.

That was definitely an intentional aspect of the spell; it's supposed to provide battlefield control worthy of a 6th level slot.



My first read, the spell looks good, sacrificing knockdown power with defense and control in a way that doesn't seem to have an autowin.

Thank you! That was the goal.



I do have some requests:

Excellent! I like suggestions.



1) Limit the "all structures are destroyed" bit. Or, just be a bit more clear about the rules to prevent using this spell to tunnel "four 20x20 squares that way".

My intention here was two-fold; first, I tried to bake in enough room in the power budget to give it some siege power. I imagine the caster using it to bring down castle gates, city walls, or towers. The auto-knockdown is something I'm concerned about at this level - though I did think that making it require concentrating for 10 rounds to pull off was a good balancing factor.

Second, I intend this to be something of a plot-power, actually. This scepter was commissioned and (in part) enchanted by Asmodeus, and is a part of his plan to invade and capture heaven. He means to use this power to shatter the gates of Celestia.

Maybe I could scale back the effect to just a bunch of damage unless cast using a 9th (or 8th?) level slot, at which point it destroys anything.

What do you think?



2) Higher levels making the pits deeper, while yes a higher spell and therefore more "I'm done with you" power, gets closer to an "I win" effect, since climbing 30 feet in one round is not something everyone can do.

I might consider increasing the fire damage. I'm concerned that, regardless, the spell may actually prove to be too easy for most mid-high level creatures to escape.



3) Allow the caster to make smaller squares. Some dungeons don't have rooms big enough to put this down safely.

Do you mean, divide the area into smaller squares that he can arrange as he wishes, or do you mean let him make only up to 4 squares, but they can be smaller if he wants?



Do you have any wording suggestions for the changes you've advised?

[Phoenix042]

My current, revised version of the spell, taking into account a few of your suggestions. I also cut down on fluff text.


Infernal Maw
6th level conjuration

Casting Time: 1 action
Range: 200ft.
Components: V, S, M (A bit of volcanic glass and a fire agate worth at least 1000gp)
Duration: Concentration, up to 1 minute

The earth comes alive with fiery malice in an area you choose within range. Choose up to four squares within range, each up to 20ft on a side. This area becomes shot through with deep, fiery fissures.
For the duration, these fissures turn the ground into difficult terrain. When a creature enters the area for the first time on a turn or starts its turn there, the creature must succeed on a dexterity saving throw against your spell save DC or be swallowed whole by a fissure. A creature that falls into a fissure takes 3d6 fire damage, as well as 2d6 bludgeoning damage from the fall, and the creature is restrained. A creature that starts its turn inside of a fissure instead takes 3d6 fire damage (no save).
A creature restrained by a fissure can use its action to make a strength check against your spell save DC, climbing out of the fissure on a success. A creature that fails this check by 5 or more falls and takes 2d6 bludgeoning damage.
Standing structures in the area take 2d6 bludgeoning damage and 3d6 fire damage at the end of each of your turns while you concentrate on this spell.
When the spell ends, the fissures cool and close. Any creatures trapped inside are deposited on the ground they fell from, or on the nearest unoccupied space.
If you concentrate for a full minute, the fissures remain after the spell ends (though they no longer deal fire damage).
At Higher Levels: When you cast this spell using a spell slot of 7th level or higher, the fire damage increases by 1d6 per slot level above 6th. If you cast this spell using a spell slot of at least 8th level and concentrate for a full minute, standing structures over the area are completely destroyed when the spell ends. Even magical structures are destroyed by this effect.

[Phoenix042]

What kind of material components should I use? I'm leaning towards something with a gold piece cost like the fire agate, but I want to emphasize the connection not just to fire, but to geological activity as well.

Something that reminds people of old volcanic calderas, steam vents, volcanoes, etc.

What do you think?

[noob]

What kind of material components should I use? I'm leaning towards something with a gold piece cost like the fire agate, but I want to emphasize the connection not just to fire, but to geological activity as well.

Something that reminds people of old volcanic calderas, steam vents, volcanoes, etc.

What do you think?

A sphere of magma.
Yes you need fire immunity to cast the spell.
Does not matter since it is a spell on an item probably created by demons or something like that.

[Segev]

Why a level of exhaustion on top of the spell slot? Is this meant to be more powerful than most sixth level spells? It being on a magic item justifies having it at all, so you don't need to add exhaustion as a tax for having the option to cast it at all.

This seems like a powerful BFC spell; I'd compare it to solid fog and poison cloud for its damage-dealing and ability to restrict movement.