Arcane Bolt

A glowing orb of stirring lightning streaks toward a creature of your choice within range. Make a ranged spell attack against the target. On a hit, the target takes 4d6 lightning damage.

On a hit, you can choose to arc the bolt to another target within 10 feet, choosing a number of d6 to divert from the main damage. 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.