Blood Lash

You draw your own blood to create a long, bloody whip that lashes out at a target in range. Make a melee spell attack against the target. If the attack hits, you take 1d4 necrotic damage, which can't be prevented or reduced in any way, and the target takes 1d12 necrotic damage. If the target is a creature, it can't regain hit points until the start of your next turn.

At Higher Levels. The damage dealt to the target increases by 1d12 when you reach 5th level (2d12), 11th level (3d12), and 17th level (4d12).