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

Push Back the Dead!

FEAT 4
UNCOMMONARCHETYPEAUDITORYEMOTIONSTANCE
Activity 1 action
Archetype Marshal
Prerequisites Marshal Dedication

You call to your ally and strengthen their resolve and abilities to defend against the horrific tricks undead bring to bear. The ally gains a +2 circumstance bonus to saves against effects originating from undead. It also gains resistance to damage from Strikes made by undead creatures equal to half your Charisma modifier.

Effect: Push Back the Dead!

Pathfinder Lost Omens Knights of LastwallOGL