Corokash's Lightning Storm

A storm rages as bolts of lightning plummet to the ground on your location. Pick up to 4 creatures and/or locations, or target multiple strikes on one creature or creatures within range. Each creature must make a Dexterity saving throw. The lightning strikes spread around corners. For each individual lightning strike on creature, it takes 15d6 lightning damage and 15d6 force damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one lightning bolt is affected only once unless specifically targeted.

Once cast, the caster takes one level of exhaustion.

The spell damages objects in the area and ignites flammable objects that aren't being worn or carried.