Yin Soul Drain

A Yin-Yang symbol appears above your head. You point at one creature you can see within range, and the yin-yang symbol will spin and shoot a black energy beam at the target. The target must succeed on a Wisdom saving throw or take 1d6 poison, psychic, cold, radiant, or lightning damage, user's choice, and you gain temporary hit points equal to half the amount of poison, psychic, cold, radiant, or lightning damage dealt. On a successful save, the target takes half as much damage only.

The spell’s damage increases by one die when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6). 

You can only gain temporary hit point up to half the max damage of this spell (minimum of 1 Temporary Hit Point).