How to properly create traps

[Olfgar]

Hey, first time DM here. Im setting up for a campaign, and Im tyring to learn ho to properly make traps. This is probably really obvious, but I dont understand something in the DM's guide.

It says the trapmaker sets the traps attack bonus, and that traps can have strength bonuses. What I want to know is, how do you determine its attack bonus, strength bonus or save DC's if its a magical trap. And If its a mechanical trap, does it get an attack roll along with the attack bonus and strength if it has one (again, how does it have strength?).

[TuggyNE]

Magical traps are defined by casting spells when triggered; they therefore generally do not use attack rolls. Mechanical traps may use attack rolls as normal, adding their total attack bonus (i.e. 1d20+11), and add their strength bonus to damage as though they were a regular weapon (i.e. 1d8+4); ranged traps have a special note that they can be customized like composite bows to make use of this strength bonus. (Presumably this additional damage comes from the use of heavier springs or counterweights in most cases.)

In other words, as far as I can tell, you basically just make up whatever base attack and strength bonuses you want, then calculate the results as though the trap were wielding a weapon in the usual way.


Ranged Attack Traps
These traps deal whatever damage their ammunition normally would. If a trap is constructed with a high strength rating, it has a corresponding bonus on damage.

Melee Attack Traps
These traps deal the same damage as the melee weapons they “wield.” In the case of a falling stone block, you can assign any amount of bludgeoning damage you like, but remember that whoever resets the trap has to lift that stone back into place.

A melee attack trap can be constructed with a built-in bonus on damage rolls, just as if the trap itself had a high Strength score.

[Olfgar]

Cool, so, a trap with a +19 attack roll, and a strength bonus of a raginig Minotaur barbarian. sweet. But no Im kidding.

Would you say having a traps attack roll be the same as either a fighter around the same level, or perhaps a rogue? to keep it balanced?

[Mystify]

Cool, so, a trap with a +19 attack roll, and a strength bonus of a raginig Minotaur barbarian. sweet. But no Im kidding.

Would you say having a traps attack roll be the same as either a fighter around the same level, or perhaps a rogue? to keep it balanced?

It is definitely something to consider when deciding on the CR of the trap. However, its nothing so simple. For instance, look at these two CR 1 traps from the DMG:

Swinging Block Trap: CR 1; mechanical; touch trigger;
manual reset; Atk +5 melee (4d6, stone block); Search DC 20; Disable
Device DC 20. Market Price: 500 gp.
Wall Blade Trap: CR 1; mechanical; touch trigger; automatic
reset; hidden switch bypass (Search DC 25); Atk +10 melee
(2d4/×4, scythe); Search DC 22; Disable Device DC 22. Market
Price: 2,500 gp.

Both are CR 1, but they have very different attack bonuses, and very different damages. The +5 is in line with a 1st level fighter(1 BaB, +4 str), but the +10 is notably higher.

[TuggyNE]

Cool, so, a trap with a +19 attack roll, and a strength bonus of a raginig Minotaur barbarian. sweet. But no Im kidding.

Would you say having a traps attack roll be the same as either a fighter around the same level, or perhaps a rogue? to keep it balanced?

Use whatever you want, as long as you follow the guidelines for calculating CR. If you crank it up really high, it'll be worth a lot of XP for defeating. :smallwink:

[Olfgar]

Touche, and with traps, defeating can also mean set it off lol. “congrats you recieve enough xp to level up...but you died from damage.“