uncommon cleric necromancy negative 

Domain undeath

Cast [>>] somatic, verbal

Range touch; Targets 1 willing undead creature

Duration 1 minute

You embed a seed of negative energy in an undead creature, restoring its unnatural vigor. The target gains fast healing 7.

This healing comes from negative energy, so it heals the undead rather than damaging it.

Heightened (+1) The fast healing increases by 2.

Core Rulebook, page 394.