Tesla's Shocking Sphere

Bolts of plasma arc from your body in all directions. They form a dome like area with a radius of 15 feet for the duration. The speed and accuracy of their strikes leaves no room to dodge.

When you cast this spell, you can designate any number of creatures you can see to be unaffected by it. An affected creature's speed is halved in the area, and when the creature enters the area for the first time on a turn or starts its turn there, it must make a Constitution saving throw. On a failed save, the creature takes 3d8 lightning damage. On a successful save, the creature takes half as much damage. Three such failures causes a creature to become paralyzed and automatically failing futher saves from this spell until they are removed from the spell’s area of effect for 1 minute.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 2d8 and increases the radius by 5 feet for each slot level above 3rd.