Chaotic bolt

You create two large purple orbs that float in a space 5 ft in front of you every time your turn starts the orbs move 5 ft forward and 5 ft away from each other. The orbs disappear once they hit an object or a creature. If a creature gets hit by the orbs they must make a dexterity saving through. On a failed save thee creature take 8d6 force damage and half as much on a success.  

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you add 1d6 for each slot level above 4th.