Azareck's Bolts of Divine Madness

You summon a storm the unleashes the divine wrath of the Mad God in a 1000 ft radius, which lasts for 24 hours. A giant bolt of destructive lightning bursts from the sky crashing to a point you can see within range. This bolt is so intense that it will cut cut through reality itself to reach it's target location. Each creature in a 80-foot-radius cylinder, that extends up to the void, at the location in range that you choose, must make a Dexterity saving throw, or take 10d12 Radiant/Force/Necrotic (your choice) damage and 10d12 Lightning damage, or half as much on a success. Those effected must also make a Wisdom saving throw, on a fail they are stunned for 1d4 turns and they gain a trait of Indefinite Madness.

On each of your successive turns until the storm ends, you can use an Action to call lesser lightning bolts. You choose a location under the storm cloud, and a bolt of lightning flashes to that point. Each creature within 10 ft of that point must make a Dexterity saving throw, or take 5d10 Radiant/Force/Necrotic (your choice) damage and 5d10 Lightning damage, or half as much on a success. They must also make a Wisdom saving throw, on a fail they are stunned until their next turn and gain a trait of Short Term Madness. 

While they are stunned they have vulnerability to Psychic damage.