Calamity of the skies

You call down a titanic meteor from the heavens to sunder the world beneath it. The sky fractures with a cold, ringing crack; a burning spear of stone and metal hurtles from the firmament, trailing a comet-tail of ionized wind. When it strikes, the impact obliterates the ground and batters living things with a concussive surge of stone and kinetic force, while heat and ember bloom outward in a vast ring.

When you cast the spell, choose a point you can see within range. A meteor descends and impacts that point. The strike has two overlapping effects:

• Primary Impact Blast 20-foot radius: Each creature within the 20-foot-radius primary blast must make a Dexterity saving throw. On a failed save, a creature takes 5d100 + 5d20 bludgeoning damage. On a successful save, the creature takes half as much damage. The meteor smashes terrain, creating difficult terrain and a crater at least 10 feet deep and 40 feet across centered on the impact point; structures and objects in the primary blast are subjected to the damage and treated as the same area’s effects.
• Secondary Fireburst 100-foot radius: After the impact, all creatures within 100 feet of the impact point (including those in the primary blast) must make a Dexterity saving throw. On a failed save, a creature takes 9d4 fire damage. On a successful save, the creature takes half as much damage. Flammable materials within the secondary radius ignite; ongoing fires caused by the blast persist until extinguished by normal means.