Darastrix's Shocking Lightning

Holding your hands together, you fire a beam if lightning 100 feet long and 5 feet out from your hands in a direction you choose. Each creature in the line must make a Constitution saving throw. A creature takes 8d8 lightning damage on a failed save, or half as much damage on a successful one. Creatures that fail the saving throw have disadvantage on all saving throws until the end of your next turn.The lightning ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.