From Pathfinder Adventures: Troubles in Grayce, which isn't enabled.

Unstable Overlook

HAZARD 3

Stealth +5

Description A ledge overlooks a yawning chasm.

Disable DC 20 Acrobatics to tread lightly across the overlook onto more stable ground. Permanently disabling the hazard requires several hours of work and a successful DC 23 Crafting check (trained).

AC 20; Fort +12, Ref +4

Hardness 12, HP 40 (BT 20); Immunities critical hits, precision

Collapse

Trigger A Small or larger creature moves onto the weakened section of the overlook

Effect The ledge collapses. Any creature on the ledge that fails to Grab an Edge plummets 40 feet into the chasm below.

Pathfinder Adventures: Troubles in GrayceORC