Hell, the unknown

Erebantes - A Forgotten Race of Demons
Erebantes are the most ancient race of the demon world, existing long before the kingdoms. Their origins are unknown, and their power defies measurement. Even greater demons cannot determine their rank.
They can take the form of any living being or inanimate object, copying its appearance, voice, and habits. Their true form remains a mystery.
The Erebantes' greatest gift is Interweaving: by stealing souls, they create warriors from them. Weak souls become obedient soldiers, while strong ones retain their memory, character, and magic. The rarest Paragons gain a will of their own and are capable of surpassing their creator.
Their hierarchy consists of five tiers: the Unawakened, the Maskers, the Soulbinders, the Primordials, and the mysterious Nameless Origin, whose existence is unproven.
But even the Erebans have weaknesses. Complex reincarnation requires concentration, a multitude of souls threatens their consciousness, and the created warriors are capable of breaking free. Their true name may be the key to limiting their power.
Vanishing
Many millennia ago, the Erebans created an army from the souls of ancient lords. Fearing the loss of power, the demon kings united against them. Thus began the War of the Erased Names.
Chronicles claim that the race was destroyed. However, some believe that the Erebantes did not perish, but erased all traces of their existence, hiding within souls, artifacts, and living beings.
The Legend of the Forgotten
“Do not seek them among the dead. Do not trust the living. Faces are deceiving, names are false, and ancient seals are powerless against one whose existence is forgotten by history itself.
We declared the Erebantes destroyed not because we defeated them. We were simply afraid to admit that we never knew how to kill them.
If one day the throne cannot determine the rank of an unfamiliar demon, do not ask its name.
For an Erebantes tells the true name only of one whom he intends to make part of his legacy.
And if he speaks it before you… then your story is already his.” — The last entry of the Black Throne archivist.