Rope Pull
HAZARD 3 +10
This trap appears to be an obvious 10-foot-deep pit with angled walls to prevent easy escape, but the true danger is represented not by the hole in the ground but from a set of loose stones in the ceiling. A knotted rope hangs from a beam above, seemingly to provide an option to swing across the pit, but any weight on the rope pulls down large, heavy boulders stacked far above.
DC 20 Thievery (trained) to tie off the rope to a more solid support
Boulders from Above
A Small or larger creature or equivalent weight pulls on the rope
All creatures within the pit or adjacent to the pit take 4d6+10 bludgeoning damage (DC 23 basic Reflex save) from falling rocks dislodged from above.
Pathfinder Adventures: Troubles in GrayceORC