Draining Smite

When you hit the target your weapon pulses with crimson energy, and the attack deals an extra 3d6 necrotic damage. Additionally, if the target is a creature that isn't a construct or undead, you regain hit points equal to the necrotic damage taken by the target, or half as many hit points if the target doesn't have blood, and the target must make a Constitution saving throw.

On a failed save, the target can't regain hit points until the spell ends. It can repeat the saving throw at the end of each of its turns, ending the spell on a success.

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