So, for those that don't know, Dark Sun is a D&D setting on a desert world and the lore for that is that it used to be a verdant green world (in what is called the green age) but the wizards learned how to get slightly more arcane power at a "small" expense to the surrounding environment and surprise surprise ruined the entire planet's ecology after a couple

centuries

also the wizard who started off the whole thing, Rajaat, who ended the green age was obsessed with how Athas used to be before all these new races evolved and so he invented defiling magic in a literal bid to Make Athas Great Again

so I'm running a campaign that is set at the end of the Green Age

the PCs are members of Rajaat's "pristine empire" with the players' understanding that relatively early in the campaign their characters will be having a "oh, we are the baddies" moment

what do you need help with?

analoren: thoughts, ideas, feedback

As they are the bad guys they all get punished with death. TPK. Time to start a fresh PF2e campaign.

But seriously. What happens with the bad guys when everything green vanished?

Do they still have their powers, as their source is gone?

Are they getting blamed? Do they all flee?

Are they caught and locked into deep caverns? Which possibly have an exist to "further down" as no one ever explored them fully?

You could do some Jules Verne "Journey to the Center of the Earth" thing... where they travel down into the depths of the planet, unknown species and stuff.

Are they meant to find a solution? You could place one down there, some large rock that's gushing out water all the time, which creates a fertile environment that would allow growth again.

Would be a big adventure to transport it back to the surface of the planet. Also up there to whomever they bring it, those would probably keep it for themselves, to only re-green a smaller area and charge a lot for everything.

At least if you need an explanation why the planet still stays a desert (except a tiny spot somewhere).