pf2e.fyi
From Pathfinder Core Rulebook, which isn't enabled.

Vengeful Oath

FEAT 2
Prerequisites paladin cause

You've sworn an oath to hunt down wicked evildoers and bring them to judgment. You gain the following edict: "You must hunt down and exterminate creatures that have committed heinous atrocities." You can use Lay on Hands to damage a creature you witness harming an innocent or a ally as if it were undead; in this case, lay on hands deals spirit damage instead of vitality damage and gains the holy trait. This doesn't prevent you from healing such a creature with lay on hands; you choose whether to heal or harm.

Pathfinder Core RulebookOGL