pf2e.fyi
From Pathfinder Lost Omens Impossible Lands, which isn't enabled.

Planar Sidestep

FEAT 13
Activity reaction

Frequency once per day
Trigger A creature hits you with a melee Strike.

You shift your body briefly between planes, reducing the damage from your foe's attack. You gain resistance 25 to all damage against the triggering attack. Observers simply see you shimmer with elemental energy for a moment, just as the attack lands.

Pathfinder Lost Omens Impossible LandsOGL