The Grey Waste

Oinos, Niflheim, and Pluton — these are the fabled "three glooms" of the Gray Waste that a cutter hears so much about. This land is evil solely, and them that's here don't care if they're in it alone or together. This is the great battlefield of the Blood War, called Hades by some primes, but anyone who's ever been here knows why "the Gray Waste" says it all

Geography

The three glooms are just that, or so the chant goes — dull gray lands. The earth is gray, the sky is gray, even the petitioners here are gray. There's no color here; as soon as a sod steps onto the plane, everything he's got turns white, black, or gray. There's no sun, no moon, no stars - just gray
Oinos. This is a layer of stunted trees, roving fiends, and virulent disease, ruled by an ultroloth prince. His citadel is the great fortress Khin-Oin, the Wasting Tower. From a distance it looks like the spinal cord of some flayed beast, soaring into the air. Closer up, it takes on the form of a great tower encased by lesser towers. It's said to stand 20 miles high and have dungeons beneath it as deep, but this is some barmy's exaggeration. The tower is a necessity, for the prince of this domain constantly finds himself under attack by his rival yugoloths. The only time they unite is when threatened with another invasion of tanar'ri or baatezu troops, who use this layer as the battleground for much of their endless Blood War.
Niflheim. The second layer is more alive than the first, being free of the wasting disease that holds the land. Though the trees - mostly pines - are more abundant, they sport no color but gray. Thick mists hang among the trunks, gray-white on the gray-black background. This is the realm of Hel, from the Norse pantheon. Her palace is a great hall of wood. Deadly poisons drip from the ceiling, and the floor writhes with serpents. Reaching into this layer is a root of Yggdrasil, the World Ash. Curled around this root is a great wingless dragon Nidhogg, who forever gnaws at the root and will ultimately kill the tree. Nidhogg could be slain, but her place would be taken by one of her children, so what's the point?
Pluton. The third layer of the Gray Waste is connected to the Upper Planes by the tunnels of Mount Olympus. This layer holds willows, olives, and poplars, all black and slowly dying for want of care. This is the realm of Hades, Lord of the Dead. He lives within a palace of gray marble, protected by strong walls. The gates to his realm are beaten bronze, impossible for all but the greatest heroes to open. Just beyond is Cerberus, the three-headed dog who guards the entrance to Hades' domain. Imprisoned here are many fallen tyrants and vain heroes.
SPECIAL PHYSICAL CONDITIONS. The despair of this plane is more than symbolic. It physically settles over all who come here. Each week, travelers must successfully made a Constitution or be trapped on the Gray Waste, unable to muster the desire to leave. Once trapped, a body becomes a larva in Id6 months. Despairing travelers must be rescued by others if they are to be saved.

Fauna & Flora

Diakk, hordling, larva, night hag, and yugoloth all live in the Gray Waste. Baatezu, tanar'ri, and gehreleth can also be found on this plane, often leading armies against each other in another assault of the Blood War. Morgion (of the DRAGONLANCE saga) and Cyric, Mask, and Shar (of the FORGOTTEN REALMS setting) are also known to occupy this plane.

Natural Resources

The rare town or settlement full of people willing o do more than mope can offer some basic supplied and a place to rest, but beyond that the wastes don't have much other than death and despair. Truly foolish berks could try heading to the realm of abbathor, nicknamed glitter hell. the glow of gems and gold are the only color within the whole plane. most of the petitioners there are a greedy folk, and any valuables end up being given to the god of greed. the only goods you'll be able to get are through trade, and often you'll be stuck with the worse end of the bargain.

Type

Dimensional plane