pf2e.fyi
From Pathfinder Adventure Path: Gatewalkers, which isn't enabled.

Shadowshift Field

COMPLEX HAZARD 1
Stealth +7 (trained) to notice the air and plants wavering and shifting
Description Cross-planar seepage from the Oaksteward rebels' ritual causes shadowy warping effects to strain and damage living creatures in the forest clearing.

Disable DC 17 Arcana (trained) to will the Material Plane's hold on the area back into firmness and disable the effect for 1 hour, or Dispel Magic (1st rank; counteract DC 15) to end the effect permanently


Shadowshift (primal)
Trigger A character enters the affected area

Effect The hazard rolls initiative as the field of planar warping surges, filling the forest clearing.
Routine

Each creature in the clearing must attempt a DC 17 Fortitude save as the planar warping threatens to create microscopic tears inside their body. Fey, plant creatures, and druids are unaffected.


Critical Success As success, and the creature is healed by the primal magic, regaining 1d6 healing Hit Points.

Success The creature is unaffected and immune to the effect for 24 hours.

Failure The creature takes 1d6+3 force damage.

Critical Failure The creature takes 2d6+6 force damage.

Reset This effect continues for 1 day, after which it ends and cannot be triggered again without another ritual.
Pathfinder Adventure Path: GatewalkersORC