Arc

 A bolt of lightning bursts from you towards a target within range. Make a ranged spell attack against the target. On a hit, the target takes 1d6 lightning damage. 

If the total damage on the dice is odd, or if you rolled a 20 on the attack roll, the lightning arcs from the target to a different creature of your choice within 30 feet of it. Make a new attack roll against the new target, and make a new damage roll, which could cause the lightning to arc again.

A creature can be targeted only once by each casting of this spell.

The spell's damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).