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

Become as Spirit

FEAT 12
Prerequisites spirit grim fascination

You can move through an unwilling creature's spaces as if they were difficult terrain. Additionally, you ignore natural difficult terrain and gain a +2 circumstance bonus to Escape attempts. Whenever you destroy a thrall, you gain resistance to all damage (except force, ghost touch, spirit, or vitality) equal to half your level for 1 round.

Effect: Become as Spirit

Pathfinder Impossible MagicORC