Thor's Lightning

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many other targets with damage based on Chart, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

A target must make a Dexterity saving throw. The target takes 10d8 lightning damage on a failed save, or half as much damage on a successful one. And the Three extra bolts does 6d8 Damage on Failed Save, and half as much on Successful save.

1 Extra - 9d8
2 Extra - 8d8
3 Extra - 7d8
4 Extra - 6d8
5 Extra - 5d8
6 Extra - 4d8
7 Extra - 3d8
8 Extra - 2d8
9 Extra - 1d8