From Pathfinder Lost Omens Knights of Lastwall, which isn't enabled.

Knight's Retaliation

FEAT 8

Activity reaction

Prerequisites trained in Athletics

Trigger An undead creature within your reach critically fails a Strike against you.

You knock the enemy's blow aside and twist, unbalancing your foe. You attempt to Disarm, Shove, or Trip the triggering creature.

Pathfinder Lost Omens Knights of LastwallOGL