Durren's Kinetic Arc

Holding your hands out, electricity begins to crackle and pulse, undulating as it turns into a sphere that is launched towards a target within range. The target the sphere is centered on must make a Dexterity saving throw. A target takes 8d6 thunder damage on a failed save, or half as much damage on a successful one. After the first target is struck a number of creatures equal to your Intelligence modifier of your choosing within 30 feet are struck at with the after waves of the Arc. These additional creatures must succeed in a Dexterity saving throw or take 6d6 thunder damage.

At higher levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.