This is actually a simple but cruel trap to play upon the party. The trap may be placed on any door with a handle or knob. The floor in front of the door is actually triggered to collapse when the knob is turned or the handle is pulled. The area the trap covers is to one’s discretion. Below the floor is a pit about 30′ deep. At the bottom lies a stone, acid filled, coffin that covers the entire bottom of the pit. The coffin has its heavy lid only being held up by a single, frail, wooden stick stretching from lid to crest.
When the first unfortunate soul falls down the pit to the open coffin below they will snap the stick holding the lid open. Since the propping stick has been broken by the falling body, gravity prevails and the coffin’s lid slams down on top of its new prisoner. Now that the lid is closed the rest of the party may freely drop on top of the coffin. As the coffin trapped party member desperately tries to open the lid to his watery grave the weight of the other party members will surely hamper the victim’s efforts.
It takes a 15 strength to open the coffin lid, not counting any additional weight on top of it. The first falling victim initially takes 1d6 fall damage from the drop into the coffin. The players falling on top of the coffin take 4d6 damage hitting the lid. I prefer using acid instead of water in the coffin for it gives a sense of urgency to the situation as items begin to dissolve. Apply 2d4 acid damage to the trapped player each round they are inside the coffin. Each round a player is in the acid filled coffin make saves for their items. Oh and don’t forget that they are holding their breath. To make the trap even worse for the ones topside apply slime to the walls for a difficult climb. Now, now don’t be harsh, don’t make it green slime. If you feel kind let the door opener make a dexterity check to hold on to the door the first round. Each and every round after that they must make a strength check to keep holding on.