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

Vicious Venom

FEAT 17

Prerequisites Envenom

The venom you produce is exceptionally potent and difficult to overcome. Your vishkanyan venom gains the virulent trait, requiring two consecutive saves to reduce the venom's stage by 1. A critical success reduces your venom's stage by only 1 instead of by 2.

Pathfinder Lost Omens Impossible LandsOGL