pf2e.fyi
From Pathfinder Dark Archive (Remastered), which isn't enabled.

All in Your Head

FEAT 18
Activity reaction

Trigger You're about to attempt a Fortitude save or a Reflex save.

Flames scouring at your body, venom coursing through your veins-you refuse to believe they exist, and nothing can affect you if you don't believe in it. You attempt a Will save against the triggering effect, instead of a Reflex or Fortitude save. You don't gain the benefits of Fortress of Will or Walls of Will on this save.

Pathfinder Dark Archive (Remastered)ORC