Borrowed Vitality

You learn to pull strength from harm and redistribute it.

Whenever a creature with blood fails a saving throw against one of your wizard spells of 1st level or higher, you gain temporary hit points equal to the spell’s level + your Intelligence modifier.

Also, when a creature with blood within 60 feet of you takes necrotic damage from one of your wizard spells or Blood Mage features, you can use your reaction to transfer vitality to another creature you can see within 30 feet of you, including yourself. The chosen creature regains hit points equal to half the necrotic damage dealt to the first creature, rounded down.

You can use this healing reaction a number of times equal to your proficiency bonus per long rest.