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

Cloak of Devouring Thorns

ITEM 12

RARE INVESTED PRIMAL

Price 2000 gp

Usage worn cloak

Bulk L

This cloak appears to be woven from a thousand living leaves, hungry for flesh and eager to defend the cloak's wearer.

Activate—Bite Back (concentrate)

Frequency once per round

Trigger You are damaged by a melee attack from an adjacent creature

Effect The leaves lash out at your attacker, rising up to reveal snapping jaws made of wicked thorns. The triggering creature must attempt a DC 30 Reflex saving throw.

Success The creature is unaffected.

Failure The creature takes 2d6 piercing damage.

Critical Failure The creature takes 4d6 piercing plus 3 bleed damage.

Pathfinder Adventure Path: GatewalkersORC