Arc Lighting

You create a bolt of lighting that arcs towards a target of your choice that you can see in range. The target must make make a dexterity saving throw. The creature takes 4d8 lightning damage on a failed save, or half as much on a successful one.

Lightning arcs from the creature, and you are able  to target up to 2 additional creatures within 20 feet. Those creatures must make dexterity saving throws. The first targets takes 3d8 lightning damage and the second 2d8 lightning damage on a failed save, or half as much on a successful one. You cannot target a creature with more than one bolt.

At higher levels. When you cast this spell using a spell slot of 3rd level or higher, the damage (both initial and arcs) increases by 1d8 damage, and one additional arc leaps from the first target to another target, for each slot above 2nd.