With a buzzing electric groan, conduits to the Elemental Plane of Air open up at four different points you can see within range and pummel the area beneath them.

Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw.  A creature takes 20d6 lightning damage and 20d6 thunder damage on a failed save, or half as much damage on a successful one. The sphere spreads around corners.  A creature in the area of more than one lightning strike is affected only once.

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