Death Dells

Yeenoghu rules a layer of ravines known as Death Dells. Here, creatures must hunt to survive. Even the plants, which must bathe their roots in blood, snare the unwary. Yeenoghu’s servants, helping to sate their master’s hunger as he prowls his kingdom seeking prey, capture creatures from the Material Plane for release in the Gnoll Lord’s realm. (Source: DMG D&D 5e)
422nd layer of the Abyss.
Yeenoghu referred to his layer of the Abyss simply as his realm, but to others it was known as the Seeping Woods or Death Dells. The plane was covered in barren hills, great ravines, wide savannas with poisonous and parasite-filled waters, and sickly yellow forests. It served as his own personal hunting grounds, where he played with mortals in cruel hunting games. There were nearly no structures in his realm, it being entirely devoid of civilization.
Six miles from Yeenoghu's lair all predators became wasteful and savage, killing far more than required and leaving it to rot in careless displays of wastefulness. Within a mile of Yeenoghu's personal lair was a dangerous region influenced by his dark powers. Iron spikes grew out from the ground and stone, which Yeenoghu used to impale his victims, and intelligent beings that spent an hour within this region might grow increasingly deranged. The longer sentient beings remained in this region the more gnoll-like they became with mental changes including increased rage, aching blood-lust, hatred of civilization, the need to collect trophies from bodies, and a fondness for the flesh of intelligent beings.
Within the smoke-filled halls of his lair he sat upon a throne of dismembered limbs of those who'd angered him. His lair was populated with gnolls, hyenas, and ghouls. It was a place of blood and death from which he could exert a certain level of control. He could cause iron spikes to rise from the ground and impale those underneath them, as well as fill gnolls and hyenas with a bloodthirsty rage. The lair itself was a giant mobile fortress-city, pulled by legions of slaves and demonic creatures on hundreds of stone wheels.(https://forgottenrealms.fandom.com/wiki/Yeenoghu#:~:text=Yeenoghu%20(pronounced%3A%20%2Fji,him%20and%20his%20rabid%20slaughter.)

Alternative Name(s)

Seeping Woods

Type

Dimensional plane

Location under

The Abyss

Owner/Ruler

Yeenoghu

Ruling/Owning Rank

Demon Lord