Armitage's Ball Lightning

You create four tiny balls of lightning in your space. They orbit around you in non-intersecting elliptical patterns for the spell’s duration. When you cast the spell — and as a bonus action on each of your turns thereafter — you can expend one or two of these balls, hurtling them in a line 5 feet wide and 120 feet long. The first two creatures hit by a ball must make a Dexterity saving throw. The creatures takes 2d6 lightning damage on a failed save, or half as much damage on a successful one. If a creature is wearing armor made of metal or has taken lightning damage since the start of its last turn, it makes the save at disadvantage.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the number of balls created increases by two for each slot level above 2nd.