https://www.dndunleashed.com/home/new-spells-greater-blood-magic
Blood Extraction
3-level Necromancy
Casting Time: 1 action
Range/Area: 120 ft
Components: V, S
Duration: Concentration, up to 1 minute
Attack/Save: Constitution Save
Damage/Effect: Necrotic
You conjure a pulsating orb of red energy floating in the air at a point you can see within range. At the end of each of your turns until the spell ends, each creature other than you within 20 feet of the orb must make a Constitution saving throw. On a failed saving throw, a creature takes 3d6 necrotic damage, or 3d10 necrotic damage if its hit points are less than or equal to half of its maximum hit points. On a successful saving throw, a creature takes half damage.
If a creature is reduced to 0 hit points by this spell, the orb collects some of its blood. It cannot collect blood from the same creature twice. When the spell ends, you are strengthened by the accumulated blood, instantly granting you 3d4 temporary hit points for each creature the orb collected blood from.
Creatures without blood are immune.