Blackbolt

You are able to manifest the lightning native of the Shadowfell, an amalgamation of electricity and necrosis. Using ancient magic learned from Shadar-kai witches, you produce a bolt of black lightning. This black lightning forms a line 100 feet long and 5 feet wide, and blasts out from you in a direction that you choose. Each creature in the line of the black lightning must make a Dexterity saving throw. A creature takes 4b8 lightning damage and 4d8 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 5th level or higher, the damage increases by 1d8 for both lightning and necrotic each slot level above 4rd.