You drain the life from the creatures around you. Each other creature within a 10-foot radius sphere centered on you must make a Constitution saving throw or take 6d8 necrotic damage on a failed save, or half as much on a successful save. Plants have disadvantage on this saving throw, and undead and constructs are immune to this spell.

The next damage roll of a spell you cast deals extra damage equal to half the necrotic damage this casting of the spell dealt.