Hades

The layers of Hades are called the Three Glooms — places without joy, hope, or passion. A grey land with an ashen sky, Hades is the destination of many souls that are unclaimed by the gods of the Upper Planes or the fiendish rulers of the Lower Planes. These souls become larvae and spend eternity in this place that lacks a sun, a moon, stars, or seasons. Leaching away colour and emotion, this gloom is more than most visitors can stand. The “Shadowfell Despair” rule earlier in this chapter can be used to represent a visitor’s despair. (Source: DMG D&D)

Oinos- The first layer of Hades was named for the lord of the daemons (the Oinodaemon), Anthraxus the Decayed. Oinos was the land of disease with stunted and withered plants amid grey rocky terrain. The river Styx flowed through this layer and there were portals to Carceri, Gehenna, and Sigil that looked like huge spinning metal coins, visible for miles/kilometres, often guarded by iron fortresses. Anyone walking this land or floating on the river Styx had a chance of contracting a major disease. Many of the daemons and some of the other creatures from the lower middle planes who were immune to disease made their home here.
Niflheim- Compared to Oinos, the terrain in the second layer was rougher, like foothills, with cooler temperatures, healthier vegetation including pine trees, and no disease. Everything was cloaked in dreary fog and mist, limiting vision to about a hundred feet (thirty meters). Yggdrasil's roots reached Niflheim, connecting it to Asgard in Ysgard. This is where Tage's home is, a castle made out of Ice. Those souls that came to worship and be with Tage don't turn into Larvae.
Pluton- The lowest level of Hades contained the base of Mount Olympus, a direct conduit through the Astral Plane to the plane of Arborea. The grey motif continued throughout this layer but most of the vegetation was black willow trees and dry, dying poplars.
Inhabitants- The daemons were the presumed rulers of Hades, but were actually outnumbered by the bird-like diakk and the greater powers had no trouble carving out realms for themselves. Factions of demodands carried on a low-level insurgency, sniping at the daemons but generally avoiding large-scale conflict that might attract the attention of the resident deities. Also known to inhabit all layers of Hades were achaierai, nightmares, mephits and night hags. (https://forgottenrealms.fandom.com/wiki/Hades)

Alternative Name(s)

The Grey Waste

Type

Dimensional plane

Location under

Outer Planes

Owner/Ruler

Tage

Ruling/Owning Rank

God