From Pathfinder Adventure Path: Hellbreakers, which isn't enabled.

Stair Spikes

HAZARD 4

Stealth +12 (trained)

Description A set of Hidden spikes stabs into the feet of anyone on the landing or front stairs.

Disable DC 22 Thievery (trained) to unhook the pressure plate or DC 24 Crafting (trained) to block the spikes

Look Sharp

Trigger The door is opened while someone is standing on the stairs

Effect Spikes fire upward, dealing 2d8+5 piercing damage to all creatures standing on the landing or stairs (DC 25 basic Reflex save). On a failure, the creature takes a –5 status penalty to its Speed for 1 hour; on a critical failure it's also Clumsy 1.

Pathfinder Adventure Path: HellbreakersORC