Black Harvest

 Ghostly blades that harvest life manifest in the area in front of you and transfer some of the living's energy to you. All creatures in a 15-foot cone originating from you must make a Constitution saving throw, taking 5d6 necrotic damage on a failed save or half as much on a successful one. 

Constructs take no damage from this spell.

Creatures within 5 feet of you have disadvantage on the saving throw.

For each creature that failed its saving throw, your next weapon or spell attack that hits before the end of your next turn deals an additional 2 necrotic damage.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the spell damage increases by 1d6, and the attack damage buff increases by 1, for each slot level above 3rd