pf2e.fyi
From Pathfinder Lost Omens Knights of Lastwall, which isn't enabled.

Repulse the Wicked

FEAT 6
ARCHETYPE
Activity reaction
Archetype Lastwall Sentry
Prerequisites Lastwall Sentry Dedication
Trigger An undead within your reach critically fails an attack roll targeting you.

You use your foe's failure as an opening to push them away. You attempt to Shove the undead.

Pathfinder Lost Omens Knights of LastwallOGL