A not-well-hidden pit trap, likely with an edge latch that can give way when enough weight goes on it, about 100 lbs. or so. It can take anyone who treads on the 3-hex lid, and can take more than one man at a time. A spring snaps the lid back into place once the victims fall off it.
Detect: Per-based Traps at -1.
Disarm: DX-based Traps.
Circumvent: DX or Jumping at -2.
Evade: Dodge at -1 to catch the edge.
Effects: 2d+2 impaling from a 7-yard fall for anyone on the 3-hex lid.
A 13-yard fall does 3d+1 impaling damage to anyone on the 3-hex lid; a 20-yard fall does 4d impaling damage; a 25-yard fall does 4d+2 impaling damage.