Beam of life siphoning

A target must succeed on a wisdom saving throw or take 4d6 necrotic damage or half as much on a successful save. You regain hit points equal to all damage dealt on a failed save, you regain no hit points on a successful save. You may keep casting the spell as an action without using a spell slot until the duration is finished.

Damage increases by 1d6 for every level above 5th that the spell is cast at.