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

Life Siphon

FOCUS 4
UNCOMMONCONCENTRATEFOCUSHEALINGWIZARD
Cast
Trigger You expend one of your wizard spell slots to cast a wizard spell of the necromancy school.

You use some of the spell's magic to heal yourself, regaining 1d8 Hit Points per rank of the spell.

Pathfinder Core RulebookOGL