Crushing Room Trap
Beyond a metal door lies a 15 by 15-foot room, its walls and floor covered in brownish stains. On the far side of the room is a 2-foot-tall alcove.
The metal door automatically snaps shut and locks 30 seconds after it is opened. When the door closes, two opposite walls begin moving inward. Roll initiative. Each round on initiative count 10, the room narrows by 3 feet. When the room reaches a width of less than 5 feet, Medium creatures must squeeze. When it reaches 0 feet, each creature inside the room takes 49 (14d6) bludgeoning damage. The walls then retract to their starting position, the door unlocks, and the trap resets.
Alcove. The alcove is wide enough to fit a single Small creature or a Medium creature that makes a DC 15 Dexterity check. A creature inside the alcove avoids the crushing walls. The alcove contains a Treasure Hoard or a Minor Treasure.
Door. The iron door is an object with AC 17, 100 hit points, and immunity to piercing, slashing, lightning, poison, and psychic damage. Forcing open the door requires three Strength checks. The door has no lock, but it has two hinges. Each hinge can be removed with a thieves’ tools check. The door falls off when both hinges are removed.
Exploration. A Perception check or an examination of the door before it closes reveals that the door is on a spring and closes by itself. An Engineering check or an examination of the lock or handles reveals that it has an automatic locking mechanism that prevents it from being opened from the inside. An Investigation check or an examination of the floor or walls reveals that the brownish stains are dried blood, and that the floor and walls aren’t mortared together; rather, the walls seem to rest on the floor.
- A creature that can reach both walls (most creatures have a reach approximately equal to their height) can make a Strength check to keep the walls apart.
- A creature using an object wide enough to reach both walls can make a Strength check with advantage to prop open the walls. On a Critical Failure, a nonmagical object is destroyed, and a magical object is damaged. A magical object damaged a second time is destroyed.
- A creature can make an Engineering check to determine how best to slow the walls. Success or failure on this check doesn’t result in a trap Success or Failure. A success on this check grants advantage to the next ability check made against the trap within the next minute.
- With a Strength check, a creature can jam spikes under the walls, triggering a Success.
Potential Outcomes
Critical Failure or Failure. The walls continue closing.
Success. The walls stop moving until the end of the triggering creature’s next turn.
Critical Success. The walls move 3 feet apart. Moving the walls so that they are 15 feet apart disables the trap.