Vitality Siphon

You tether yourself to a living creature within range. The target must make a Constitution saving throw. On a failed save, the target takes 3d6 necrotic damage, and you regain hit points equal to half the damage dealt.

On each of your subsequent turns for the duration, you can use your action to automatically deal 2d6 necrotic damage to the tethered creature and heal for half that amount.

The spell ends if the target moves more than 60 feet away from you or if it has total cover from you.