Aegioch's Apocalypse

Using a huge amount of dark magic, you attempt to speed up the destruction of the world. Make a DC 18 Wisdom Saving throw. On a fail, you die and can't be revived in any way. On a success, the following happens to the planet:

-rain is now fire. Targets take 3d10 fire damage per round exposed to the fire rain. Flammable objects burn under the rain.

-giant earthquakes, storms, and floods are commonplace. Few structures last long.

-portals to the elemental planes, the Abyss, and the Nine Hells are found every couple miles. Wars between them are everywhere.

-the Weave seems to falter. Whenever you use magic, roll a d20. On a 16 or above, offensive spells are cast back at the caster, buff spells are cast at the enemy, and other spells fail entirely. Magic items that fail the check explode, dealing Xd12 force damage, where X is 2 times the rarity: 1 for common, 2 for uncommon, and so on.

if this goes on for 200 years, the planet implodes, destroyed utterly. If the caster is killed and wish is cast up to 30 ft away from the corpse, the spell ends.