CR for Simple Traps (5e Variant Rule)

CR for Simple Traps

"Okay, we made it past the hallway of pits, dodged under the swinging blades, held our breath through the chamber of gas and only just escaped with the treasure! Quite the experience for our adventuring party! Did we level up?"

"Eeeh, nope. 0 XP each."

In default play, simple traps in 5th edition do not grant experience points.

This variant rule treats simple traps like monsters for the purpose of assigning them a Challenge Rating. The principle is that a trap is not dissimilar to a monster: encountering one uses up party resources (such as hit points) and may require checks to overcome or bypass. Even an easy-to-spot-and-bypass simple pit trap can be given a CR value, much like an unthreatening monster like a rat is given a CR – ultimately the DM still decides whether or not to award the XP.

Traps with CR can also be used when building combat encounters, substituting some monsters for traps. When you do this, assume that the monsters know about the traps. If intelligent, monsters will use such traps to their advantage.

Calculating CR

The method presented in the Dungeon Master's Guide (p. 273) is used. Since a simple trap is "defeated" as soon as it is triggered (requiring a reset before it can trigger again), its Defensive CR is always 0. When determining Offensive CR, the average damage/round over 3 rounds is considered, so in most cases this will simply be the trap's damage divided by 3. If a trap automatically deals damage without an attack roll or saving throw, the DC of the check required to spot or investigate the trap is used. Some traps automatically reset, and are in principle able to trigger every round, but it is assumed that the players will avoid deliberating triggering it again.

Example Traps

The following are the 3rd edition sample traps converted to 5th edition and assigned a CR. Skill checks and triggers are presented in a compact form, refer to Dungeon Master's Guide p. 120 for more information.

• Most pressure plates can be prevented from activating by wedging an iron spike under it.
• Traps with attacks are unaffected by vision-related effects.
• Disarm checks are Dexterity check using thieves' tools.

Basic Arrow Trap (CR 1/4)

Mechanical; 20-lb pressure plate (Investigate DC 15)

The arrow hole (spot DC 15) may be up to 80 feet away from the pressure plate.

One arrow attacks the triggering creature.

Arrow (1/reset). Ranged Weapon Attack: +5 to hit, one target. Hit: 3 (1d6) piercing damage.

Camouflaged Pit Trap, Small (CR 0)

Mechanical; 5-foot square covered pit (spot DC 15)

Creature stepping onto the cover falls 10 feet.

Deeper Pit Trap (CR 1/4)

Mechanical; 10-foot square covered pit (spot DC 15); hidden switch bypass (spot DC 20)

Creatures stepping onto the cover fall 20 feet.

Fusillade of Darts (CR 1/8)

Mechanical; 20-lb pressure plate (Investigation DC 15)

The dart holes (spot DC 15) may be up to 20 feet from the pressure plate.

Four darts attack random targets within 10 feet of the pressure plate.

Dart (1/reset). Ranged Weapon Attack: +5 to hit, one target. Hit: 3 (1d4 + 1) piercing damage.

Poison Dart Trap (CR 0)

Mechanical; 20-lb pressure plate (Investigation DC 15)

The dart hole (spot DC 15) may be up to 20 feet from the pressure plate.

One poison dart attacks the triggering creature.

Bloodrot-Poisoned Dart (1/reset). Ranged Weapon Attack: +4 to hit, one target. Hit: 2 (1d4) piercing damage and the target must make a DC 12 Constitution saving throw. On a failed save, the target is poisoned for 8 hours.

Poison Needle Trap (CR 1/8)

Mechanical; touch trigger (Investigation 20, disarm DC 15)

One poisoned needle hits the triggering creature. The trigger is typically opening a chest or other container.

Greenblood Oil Needle (1/reset). 1 piercing damage and the target must make a DC 13 Constitution saving throw, taking 1d10 poison damage on a failed save or half as much on a successful one.

Portcullis Trap (CR 1/4)

Mechanical; 20-lb pressure plate (Investigation DC 15)

The portcullis (spot DC 15) drops in its designated space, subsequently blocking the passageway. Each creature underneath the portcullis must make a DC 15 Dexterity saving throw. On a failed save, a creature takes 11 (2d10) piercing damage and is restrained until the portcullis is raised.

Razor-Wire across Hallway (CR 1/4)

Mechanical (spot DC 15); line across a 10-foot wide passage (disarm DC 10)

Razor-wire (1/reset). Melee Weapon Attack: +5 to hit, each target moving into the line. Hit: 11 (2d10) slashing damage.

Rolling Rock Trap (CR 1/2)

Mechanical; 20-lb pressure plate (Investigation DC 15)

A 3-foot-diameter stone sphere is released from a hidden trapdoor (spot DC 15); initiative +8, speed 60 feet. The sphere's space is difficult terrain, and the sphere can move through other creature's spaces. While the sphere is rolling, if a creature enters its space or the sphere enters a creatures space, that creature must make a DC 15 Dexterity saving throw, taking 11 (2d10) bludgeoning damage on a failed save and be knocked prone.

As an action, a creature within 5 feet of the sphere can attempt to slow it down with a DC 15 Strength check. On a successful check, the sphere's speed is reduced by 15 feet. If the sphere's speed drops to 0, it stops moving and is no longer a threat.

Scything Blade Trap (CR 0)

Mechanical; 20-lb pressure plate (Investigation DC 15)

One scythe (spot DC 15) attacks the triggering creature.

Scythe (1/reset). Melee Weapon Attack: +4 to hit, one target. Hit: 4 (1d8) slashing damage.

Spear Trap (CR 0)

Mechanical; 20-lb pressure plate (Investigation DC 15)

The spear hole (spot DC 15) may be up to 200 feet from the pressure plate.

One spear attacks a random creature in a 5-foot line from the spear hole to the pressure plate.

Spear (1/reset). Ranged Weapon Attack: +6 to hit, one target. Hit: 4 (1d8) piercing damage.

Swinging Block Trap (CR 1/8)

Mechanical; touch trigger (Investigation 20, disarm DC 15)

One swinging block attacks the triggering creature. The trigger is typically opening a door, with the block on the other side.

Swinging Block (1/reset). Melee Weapon Attack: +3 to hit, one target. Hit: 16 (3d10) bludgeoning damage.

Wall Blade Trap (CR 1/8)

Mechanical; touch trigger (Investigation 20, disarm DC 15); hidden switch bypass (spot DC 20); automatic reset

One blade (spot DC 15) attacks the triggering creature then resets itself.

Blade. Melee Weapon Attack: +5 to hit, one target. Hit: 5 (1d10) slashing damage.

Box of Brown Mold (CR 1/4)

Mechanical; touch trigger (Investigation 20); automatic reset

Opening the box triggers the trap. Each creature within 5 feet of the box must make a DC 15 Constitution saving throw, taking 2d10 cold damage on a failed save or half as much on a successful one.

Bricks from Ceiling (CR 1/8)

Mechanical; touch trigger (Investigation DC 20, disarm DC 15); repair reset

The trigger is a fake door. On triggering, each creature within 10 feet of the door must make a DC 15 Dexterity saving throw, taking 5 (1d10) bludgeoning damage on a failed save or half as much damage on a successful one.

Burning Hands Trap (CR 1/4)

Magic; proximity trigger (detect or disable with Arcana DC 15); automatic reset;

dispel magic (DC 11) destroys the trap.

Burning hands (15-foot cone, 3d6 fire damage, DC 13 Dexterity save for half damage)

Camouflaged Pit Trap (CR 1/8)

Mechanical; 10-foot square covered pit (spot DC 15)

Creatures stepping onto the cover fall 20 feet.

Inflict Light Wounds Trap (CR 1/8)

Magic; touch trigger (detect or disable with Arcana DC 15); automatic reset

dispel magic (DC 11) destroys the trap.

A creature touching the trapped object is struck with the inflict wounds spell, and takes 3d10 necrotic damage (no attack roll required).

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