Arc Lightning

You create a harsh arc of lightning energy that strikes at one creature of your choice that you can see within range. The target must succeed on a Dexterity saving through or take 2d8 Lightning damage, or half as much on a success. Then choose a creature within 20ft. of the first creature. The second creature must succeed on a Dexterity saving throw or take 2d6 Lightning damage, or no damage on a success. If there is no creature within 20 feet of the first creature, the lightning harmlessly strikes the ground. Creatures composed of, or wearing, metal have disadvantage on this saving throw.

At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 on the first target, and 1d6 on the second target for each slot level above 2nd.