Draining Kiss

You drain the life from those you kiss. The target must make a Constitution saving throw contested against your spell save DC, taking 2d10 + your Charisma modifier Psychic damage on a failed save, and half as much on a passed save.  You gain a number of temporary hit points equal to half of the damage dealt rounded down. The target's hit point maximum is reduced by the number of Psychic damage. The target dies if this effect reduces its hit point maximum to 0.

The spell's damage increases by 3d10 when you reach 5th level (4d10), 11th level (5d10), and 17th level (6d10).