Destruction on a ludicrous scale

[Tal Rasha]

I'm not sure if this fits the criterion of total destruction of the material plane, but let's give it a go.

Remove every living being's ability to procreate. Plants, animals, sentients, everything. Everything ages, everything dies. Of course for the sentients it will be the most abrupt, them not having anything to eat or such. But in due time, the gods will be forced to abandon the sphere or perish themselves. The planet will no longer have a means to regulate itself, so it will either be a barren rock, will heat up to Venus levels due to increased emissions of carbon dioxide from the planet's crust, or will freeze to a crisp due to not having enough carbon dioxide left to maintain heat. If I'm not mistaken, in FR absence of any living being would also mean absence of worshippers of Mystra, which would effectively end the weave, which would allow raw magic into the world to devastating effect, following which it could end the world entirely.

Now, IMHO this scenario is still vulnerable to time-manipulation techniques. But I think it's a good starting point.

 

[Kae'Yoss]

Remove every living being's ability to procreate.

There's cosmic events that can do that.

 

[The Grumpy Celt]

The LOW open multiple rifts or gates on and in the sun to the positive energy plane. This over charges the celestial body causing it to explode, devastating the individual prime material plane. Once the sun has been demolished and the planets are burned and blown apart, and 99% percent of the life has been extinguished then the plane itself dies. It begins shrinking and then collapses.

It takes the LOW decades to accomplish this, however and at the costs of 100s of thousands of individual Locusts of Worlds.

 

[Nyeshet]

If I recall correctly, in the Forgotten Realms there is a myth about a serpent quasi-deity that will one day consume the sun. Another deity watches over where this enemical being sleeps until the end day.

What if something similar exists in your world? Perhaps some prophesy speaks of a situation that could / would bring about the end of the world, and something the PCs do causes it to start up - perhaps even early?

Maybe Ragnarok is on the horizon, and the clash of deities and elemental forces will slay nearly all - the few remaining dying in the aftermath of first icy chill and then fiery heat that destroys all the detris of the former world.

Perhaps a deity of negation / destruction has been working on a plan for some time to destroy all, and now the time has come for the initial stages to begin?


Oh, and the joke about traveling to another Prime, using the former prime as a consumed component to the spell? It reminded me rather strongly of Melancholy of Harumi for some reason.

 

[Zeit]

Go with the classic: force open a large enough hole in the crystal sphere for a prolonged amount of time. Then watch as the Phlogistion is drawn in and explodes when it hits the sun.

*boom*

There goes the entire crystal sphere. And there's canon precedence for it, even.