Death in the Abyss

The phenomenon of death occurs in every aspect of existence, but within the realms of the infinite the cycle of death and rebirth occurs within a different parameter of rules. Death as it is known in the mortal world does not exist in the realms of eternity, in its place are different cycles of reincarnation, with complete oblivion acting as the complete death for all things that exist. Denizens of the Abyss that still retain a soul or memories of their mortal life cannot "die" while in the Abyss. When a damned soul's body is destroyed, the soul and consciousness reforms into a mane, a demon of the lowest standing, from their they will have to reclimb the ladder of demon hood to their previous position. If a sinner chooses to shed their soul and any lingering memories or ties to their mortal life then they enter the Unholy Cycle.
The Unholy Cycle is the true phenomenon of death in the Abyss. Only demons, true abyssal spawn, and soulless sinners can go through this cycle. A demon does not have the luxury of being both mind and body, they are one and the same. When a demon's corporeal body is killed its consciousness and anything that resembled its personality fades into oblivion. All that remains is the infernal power that the demon once possessed, if the slayer of the demon was also a demon then a portion of this power goes to the slayer. But it's evil, it's will, and its remaining power are reformed into a new consciousness in one of the layers. This is true for all demons including the demon lords, the more powerful and evil the demon, the more powerful the next reincarnation is, this power can sometimes magnify if the hatred for the killer is strong enough or if the madness or evil of the demon is potent enough, creating a demon that is far more powerful then its previous incarnation. This cycle can be interrupted and even broken if the consciousness of a reforming damned soul and the reforming demons power and evil were to collide. This event is an extremely rare occurrence and when it does it is a near certainty that the soul of the damned will be swallowed by the demonic essence, but should the damned soul be able to keep themselves and not be erased then the result would be a being that is considered to be an abomination to even the most reviled creatures of the Abyss. A damned soul that has been immeasurably corrupted by the evil of the Abyss and given the power of one of its true residents, this union is far more powerful than either of its predecessors and if the right combination occurs can even compete with the power of the Demon Lords themselves. As a result anytime a creature like this comes into existence they are hunted down and taken before Krell the lord of the Abyss, who rips their essence in two, ending the union and sending both halves to oblivion.