Ashstar

You summon a bilious green star that hovers over an enemy. That enemy must make a Wisdom saving throw. If they fail any wounds taken while the star  is over them deals plus 1d8 necrotic damage. This extra necrotic damage cannot be healed until the enemy has completed a long rest, after which they can heal normally. You may use a bonus action to
move the star over another enemy within 30 feet.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 2nd.