Hades

The layers of Hades are called the Three Glooms—places without joy, hope, or passion. A gray 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 color and emotion, this gloom is more than most visitors can stand. The “Shadowfell Despair” rule can be used to represent a visitor’s despair.

Optional Rule: Vile Transformation

At the end of each long rest taken on the plane, a visitor must make a DC 10 Wisdom saving throw. On a failed save, the creature gains one level of exhaustion, which can’t be removed while the creature remains in Hades. If the creature reaches six levels of exhaustion, it doesn’t die. Instead, the creature permanently transforms into a larva, whereupon all levels of exhaustion afflicting the creature are removed.
A larva is a miserable fiend that retains the facial features of its previous form but has the body of a fat worm. A larva has only a few faint memories of its previous life and the statistics in the larva stat block.
Hades is crawling with larvae. Night hags, liches, and rakshasas harvest them for use in vile rituals. Other fiends like to feed on them.

Type

Dimensional plane