pf2e.fyi
From Pathfinder Lost Omens Draconic Codex, which isn't enabled.

Ferocious Will

FEAT 9
Activity reaction

Frequency once per hour
Trigger You succeed at a saving throw against a magical mental effect.

You send a blast of magical feedback at the effect's source, dealing 1d6 per 2 levels (rounded up) mental damage with a basic Will save against your class DC or spell DC, whichever is higher. If the target critically fails, it's also Slowed 1 for 1 round. At 11th level and every 2 levels thereafter, the damage increases by 1d6.

Pathfinder Lost Omens Draconic CodexORC