From Pathfinder Lost Omens The Mwangi Expanse, which isn't enabled.

Bristle

FEAT 5

Activity 1 action

You curl into a posture that splays out your bone spines. You gain a +1 circumstance to AC until the start of your next turn.

Effect: Bristle

Special If you have the Barbed Quills reaction or a quills unarmed attack, each gains a +1 circumstance bonus to damage rolls until the start of your next turn.

Pathfinder Lost Omens The Mwangi ExpanseOGL