|Trigger:Mechanical: Interaction||Effects:Never Miss|
|Resets: Automatic||Bypass: None (Avoid)|
Description: Do your players assume that they are in a super-heroic fantasy game? They won't after this pit!
There is a big open pit. It is filled with some unsavory substance (acid, magma, water with piranha, oozes, green slime, etc.)
Next to the pit is a little hook holding a rope or chain. The rope or chain is attached to the ceiling. It can easily be used to swing across the pit.
Of course once over 100 pounds of weight are applied to the rope, it disengaged from the ceiling, extending an extra 10' or so. The delver now won't clear the pit, and the thud from the smack into the opposing wall will certainly attract a wandering monster.
Detection/Disarming: Just, sometimes, it's nice to set them up.
Any player that actually examines the far side of the pit will see the impact on the far pit wall. They might also notice certain discoloration of the rope/chain from certain pit contents and rope/chain length combinations.
All in all, they deserve what they get.
As noted in the comments, credit for this idea is from Grimtooth's traps, a trademark of Flying Buffalo Inc. games.