Mass Leech

3rd-level necromancy

Casting Time: 1 action
Range: Self (20-foot-radius sphere)
Components: V, S, M (a live leech that has fed on humanoid blood in the past 24 hours)
Duration: Instantaneous
Class: Cleric, Tamer, Warlock, Wizard

You drain the life force of those around you, turning their limbs heavy and their bones cold. Each creature of your choice within 20 feet of you must make a Constitution saving throw. A target takes 2d8 necrotic damage on a failure, or half as much damage on a success. The caster regains hit points equal to half the total amount of necrotic damage dealt to Small or larger creatures.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.

Source: Heliana's Guide to Monster Hunting