Arcsphere

You launch a violently spinning sphere of unstable lightning to a point you can see within range. The sphere detonates with a surge of crackling energy, then remains suspended, lashing out at nearby creatures.

When the sphere appears, each creature within 15 feet of it must make a Dexterity saving throw. A creature takes 5d8 lightning damage on a failed save, or half as much damage on a successful one.

If two or more creatures fail this saving throw, the sphere becomes Overcharged until the end of your next turn.

At the start of each of your turns, the sphere releases arcs of lightning at creatures of your choice within 15 feet of it. Up to three creatures must make a Dexterity saving throw, taking 2d6 lightning damage on a failed save, or half as much on a success.

While Overcharged, the sphere instead targets up to four creatures and the damage increases to 2d8 lightning damage.

As a bonus action on your turn, you can move the sphere up to 30 feet to a space you can see. If the sphere moves within 5 feet of a creature, that creature takes 1d6 lightning damage.

Additionally, any creature that ends its turn within 10 feet of the sphere takes 1d6 lightning damage.