Weakness

One target creature that you can see within 60 feet makes a Constitution saving throw against your spell save DC. On a failed save, the target creature takes 6d8 necrotic damage, and its max hit points are reduced by the amount. While the creatures hit points are reduced in this way, it has disadvantage on Strength and Dexterity checks for the duration. On a successful save, the creature takes half damage and suffers no additional effects. 

At Higher Levels. If you use a spell slot of 5th level or higher, the targets hit points are reduced by an additional 1d8 for each slot level above 4th.