Crushing Walls Room (Elite)
Trap
Level 11 Elite Blaster
XP 1200

When a character moves onto a central square in the room, reinforced iron doors crash down over the exits, and two opposing walls begin to press inward. Each iron door can be opened to prevent accidental entrapment, but each door release has three locks.

Trap: One square in the room is a pressure plate that makes the walls press together when it is stepped on.Perception     DC 16: Slight scratches in the floor and ceiling make it look like the walls can move inward.     DC 21: A portion of the floor gives in when pressed down. It might be a trapdoor or pressure plate.     DC 26: A hidden slot is above each door. Something might fall out of it.Initiative +4          Speed 1(consider altering this based on the size of the room)TriggerThe trap is triggered when a creature enters the trapped square, which is typically in the center of the room. When triggered, the iron doors fall into place. Roll initiative. On the trap’s initiative count, the walls move inward.AttackStandard Action      Area the entire room
Target: Each creature in the areaEffect: On the trap’s initiative count, each wall moves inward 1 square. Creatures adjacent to the wall are automatically pushed 1 square. When the crushing walls are 1 square apart, they attack all creatures in the room until all are crushed to death.Attack: +14 vs. FortitudeHit: 3d6 + 5 damage.Miss: Half damage.Countermeasures     Thievery DC 26: A character adjacent to the trapped square can delay or disable the trigger with a successful check.
     Thievery DC 26: A character adjacent to one of the doors can disable it with a successful check.
     A character adjacent to one of the doors can use a key to open one of its three locks, assuming the character has the right key.
     Thievery DC 21: A character adjacent to one of the doors can open one of its locks with a successful check.
     Strength DC 25: A character adjacent to one of the moving walls can prevent its inward movement with a successful check. If the walls are 1 square apart, the DC increases to 26. Any number of characters can aid the one making the check.
     Strength DC 25: A character adjacent to one of the doors can attempt to break it down with a successful check.

Published in Dungeon Master's Guide 2, page(s) 68.