Realm of Final Breaths
This mycilic realm once flourished before it was conquered by plague. Now it sleeps away its last days under the harsh rule of Primal Decay. Fungal spires shoot out of the rich soil as acid rains from the miasmic clouds above. Even the rivers now run green from arcane pollution. The few sophonts that still cling to life on Morius exist solely to find a way to cure the realm... Or seek ways to complete its transformation.
Morius has three continents, each one a blighted wasteland scarred by massive vents of toxic gas. The few settlements that exist are partially buried underground and built with glass domes to keep out the toxins. Sophonts must be careful to not dig too deep and fall into the Primal Decay that boils underneath the surface.
The very air of Morius is deadly to most creatures, even many of the native creatures. This is caused by a thick miasma produced by massive, parasitic fungi.
Mutated and derranged Manfolk. Several varieties of Fungalfolk. All of them have been forced to adapt to the intense amount of Primal Decay in the realm.
The landmasses of Morius are actually decaying sections of ancient fungal shelves that grew out of the acrid seas. They once supplied nutrients for a variety of ecosystems but have now been dead for some time. Massive, parasitic mushrooms have nearly killed off all of this ancient species. These same mushrooms spread spores across the skies making the air toxic.
Fungus on Morius is often as smart as any beast. Elementals often also take on fungal forms, but they also stalk the shadows. Amphibians, reptiles, and bugs are very common. All flying creatures have basically died off.
Glow was a primary resources harvested from the fungal shelves, now to gather it Magi have to risk the deadly Parasite Shrooms.
Alchemy thrives, spellcraft thrives, other sciences have fallen behind. Many living in the dome cities have forgotten how they were even built, which eventually will lead to a collapse. For now, magic is used to patch everything together.