Force Wall Trap

The force wall trap is an easy trap to put in your scenario. All you need is a corridor with a hole in it. You can make the hole as wide as you like, just as long at it is possible to jump the distance, and keep the depth so that the players can see the trap down in the bottom of it.

In the hole you can have spikes, acid, scorpions, skeletons or what ever you find cool. Just remember, at least one player WILL end down there. 

Then, on the opposite side of the hole, you will place a force wall or another type of invisible barrier. This will completely plug up the hallway, going from floor to ceiling in full width of the corridor. Thus, when a player or more jumps to clear the hole, they will hit the invisible wall and fall down into the pit and the trap waiting, taking falling damage + whatever damage you’ve put in there.