You point your finger at a target within reach and lightning arcs towards them. Make a ranged spell attack against the target. You have advantage if the target is wearing armor made of metal. On a hit, the target takes 1d6 lightning damage. If it takes 6*, the lightning arcs to the nearest creature within 15 feet, repeating the spell attack. This bounce can happen an unlimited amount of times. 

The spells damage increases to 2d6 when you reach 5th level, 3d6 when you reach 11th level, and 4d6 when you reach 17th level.

*The damage threshold increases to 11-12 when you reach 5th level, 16-18 when you reach 11th level, and 20-24 when you reach 17th level.