Wails of the Grave

As you extend your hand out, you channel the spirits of the dead and send a ghastly wave of the voices of the dead from your outstretched hand. Each creature within a 15 foot cone must make a Wisdom saving throw. On a failed save, creatures take 2d6 necrotic damage and they cannot regain hit points until the start of your next turn. On a success, they take half as much damage and they can regain hit points as normal.

An undead who fails the save subtracts 1d4 from the next saving throw it makes before the end of your next turn as the grave calls them back to the realm of the dead.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 1.