Ball Lighting

A 5-foot wide bright sphere of crackling electricity forms at a point you choose within range.  It emits bright light for 10 feet and dim light for an additional 10 feet.

The caster can use a bonus action the caster can move the sphere up to 30 feet in any direction.  If the sphere extends past the range it dissipates harmlessly and instantly.  If the sphere makes contact with any creature or object touching the ground or the ground itself the sphere will ground itself through the creature or object and deal 3d12 lighting damage on a failed save, or half as much damage on a successful one.  Once this happens the sphere dissipates.

The caster can use their action to cause the ball of lightning to fulminate.  Once the sphere fulminates the spell ends.

When the sphere fulminates, each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 3d12 lightning damage on a failed save, or half as much damage on a successful one.

The lightning arcs around corners when it fulminates.  

At the end of the casters turn the ball of lighting will strike the closest 1d4 creatures within 40 feet.  The creatures take 1d12 lightning damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d12 for fulminate, sphere contact and 1 additional creature when the ball lightning strikes.  For example 4d12 lightning damage at level 5th level when using fulminate and when the sphere contacts a creature or object, and 1d4+1 creatures when ball lightning strikes at the end of the casters turn.