A blinding flame erupts from your palm to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 2000-foot-radius sphere centred on that point must make a Dexterity saving throw. A target takes 100d10 fire damage and 100d10 radiant damage on a failed save, or half as much damage on a successful one.
Damage bypasses resistance and immunity to fire or radiant damage, the terrain is scorched into glass, vegetation turned to ash, stone structures reduced to molten slag, any creature reduced to 0 HP is utterly disintegrated, leaving no remains.
Upon casting, you die instantly, your body and soul consumed in the flare, no resurrection not even a wish or true resurrection cast by a deity can restore you.
(Although listed as a level 9 spell, this spell would be classed as level 10)
* - (The casters life)