Dark Spear

3rd Level 

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 a line 100.ft line and 5.ft wide. Each creature in the line must make a dexterity saving throw. The creature takes 8d6 necrotic damage on a failed save, or half as much damage on a successful one.

At higher level

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.