Draining Smite

The next time you hit a creature with a melee weapon attack during this spell’s duration, your weapon carves a rift in your enemies soul, and the attack deals an extra 6d6 psychic damage to the target. The target must make a Charisma saving throw. On a failed save its hit point maximum is reduced by an amount equal to the damage taken by the attack. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.