You target a living creature with a circulatory system. The target must make a Constitution saving throw. On a failed save, it takes necrotic damage and suffers disadvantage on attack rolls and ability checks. On a successful one, it takes half as much damage and suffers no disadvantage. This spell has no effect on undead or constructs.
At higher levels
When you cast this spell using a spell slot of 4th level or higher, the necrotic damage increases by for each slot level above 3rd.