Aegioch's Instant Devastation

You invoke words of power that cause utter destruction. Choose a 20 ft cube within range. It bursts into flame. All creatures must make a Dex save, taking 8d8 fire damage on a fail, and half that amount on a success. This damage is unaffected by fire immunity or resistance and deals double damage to inanimate objects. This makes it almost certain that a huge crater will form at the point of explosion, destroying everything nearby.