pf2e.fyi
From Pathfinder Impossible Magic, which isn't enabled.

Mental Wards

CLASS FEATURE 3

You have created wards to protect yourself against the mental effects caused by undead creatures and effects. Your proficiency rank for Will saves increases to expert. When you roll a success at a Will save against a mental or possession effect caused by an undead or haunt, you get a critical success instead.

Pathfinder Impossible MagicORC