From Pathfinder Society Scenario #1-04: Bandits of Immenwood, which isn't enabled.

Ankle Trap (3-4)

HAZARD 1

Stealth +10

Description Many small pits have been dug in the road and covered with leaves and dirt to disguise them.

Disable If spotted, the pits can be avoided by moving at one quarter of normal speed.

Trip Up

Trigger A creature walks into the affected area

Effect Any creature that walks through the affected area must attempt a DC 14 Acrobatics check. Creatures that fail this check take 1d8 bludgeoning damage and a –5-foot penalty to their Speed for 1 hour. A critical failure increases the damage to 2d8 bludgeoning damage and reduces the creature's Speed by half for 1 hour.

Pathfinder Society Scenario #1-04: Bandits of ImmenwoodOGL