ball lightning

A crackling orb of lightning appears in your hand. Make a spell attack to throw the orb at a creature. On a hit, the orb explodes for 1d8 lightning damage.  Creatures in a 5ft. radius to the target receive 1d4 thunder damage. Anything hit by thunder gets a Con save. On a sucessful save they take no damage. This spell upscales at 5th,11th, and 17th level, doing 1d8 more of lightning damage and another 1d4 thunder damage per upgrade in level.