You shoot a jolt of lightning at a creature you can see within range. Make a ranged spell attack against the target. On hit, the target takes 1d8 primary lightning damage and an arc of lightning jumps from the target to another creature within 15 feet, using the same attack roll, dealing 1d4 secondary lightning damage on hit.   This spell’s damage increases by 1d8 primary and 1d4 secondary damage when you reach 5th level (2d8 and 2d4), 11th level (3d8 and 3d4), and 17th level (4d8 and 4d4).