Wrath of the Sky

You summon a roaring storm of a mile of extension, centered directly above you, it instantly starts to rain heavily, the crackling of thunder is unstoppable and the cold wind almost can cut your skin.

Recharge X–Y. The notation "Recharge X–Y" means a creature can use a special ability once and that the ability then has a random chance of recharging during each subsequent round of combat. At the start of each of the creatures turns, roll a d6. If the roll is one of the numbers in the recharge notation, the creature regains the use of the special ability. The ability also recharges when the creature finishes a short or long rest.

Lightning Strike (Recharge 5-6): When you cast this spell, choose a point you can see withing range to call upon the wrath of the sky to destroy your enemies. A great lightning bolt descends from the storm to that point. Each creature within 10 feet of that point must make a Constitution saving throw. on a failed save a creature takes 5d10 lightning and 3d8 thunder damage and falls prone, or half as much damage on a successful one. On each of your turns until the spell ends, if you have a charge you can use your action to call down lightning in this way again, targeting the same point or a different one. After the first lightning strike, each failed attempt to recharge adds 1d10 Lightning and 1d8 Thunder damage to the next strike, to a maximum of 10d10 and 8d8. If there is already a storm happening, the minimum and maximum damage of the Lightning Strike are increased by 2d10 and 2d8.