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 Exhausted, 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.

Primary Related Location

Hades