Dark Orb

You create a large black orb that seems to  sap away the light around it. The orb shoots forward in a direction you choose, hitting every creature in the line 100 feet long and 5 feet wide. Each creature in the line must make a Dexterity saving throw. A creature takes 8d6 necrotic damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.