Tempest Storm

Create a thunder storm 100ft around you in a circle that strikes all who are in it at the beginning of each round. All creatures must make a Dex save with disadvantage in order to dodge the strike. If failed, creature takes 6d6 lightning damage and attackers get advantage against creature.

At Higher Levels. At levels 4, 6, 8, and 10, each creature get struck with one more lightning bolt and adds 1d4 for each failed Dex save after the first one.