The Shattering

((This is merely a draft and may or may not change significantly as I try to cover up the copious amount of plot holes that have arisen through my super unorganized worldbuilding, names are also TBD partially))

The Shattering was a cataclysmic event that changed the foundations of the universe forever. In it, the original Lord Of Souls, [Lucifer], split his own soul (specifically the spark) into millions of pieces, shattering them amongst humanity, a race which he had favoured since it first emerged. This allowed humanity not only to use magic (by attracting and manipulating mana), but also made their souls capable of lasting on after death, although, with no afterlife existing, they would simply remain stuck in Materia.

This caused a massive shift in the divine order of the world, as, due to the modified human souls being inherently imperfect, they corrupted more and more every time a human used magic. While the humans were alive their bodies and their physical mind were usually able to hold it back, however, after death their souls lingered in their unmoving bodies and, disturbed by their state, the corruption began taking them over more and more, the soul desparately trying to use magic to get out of this situation somehow and just furthering the process.

Within a timeframe of anywhere from a few hours to multiple weeks after death, the corruption would reach a point of no return, the soul either bursting free from its body or reanimating it in a gruesome manner- either result would form horrific creatures with nothing in their hearts but hatred and hunger for all things living: the first demons.

This developement caused widespread chaos among the human world, and the divines, which had chosen to just observe at first, were struck with panic as well - the demons not only brought destruction upon [Earth], but they also appeared to seek each other out and (after a violent fight) assembled into even more dangerous beasts. If this trend continued, soon humanity would be compromised and what would remain would be the Beast of Souls, an abomination to the gods, born from the once greatest angel of them all.

This Beast would be powerful enough to constitute a threat to the universe itself and neither [God] nor Mors appeared interested in intervening yet, merely watching the event unfold with great interest - this was certainly a developement neither of the two had expected.

The divines had to do something by themselves if they wanted life to continue existing, and they had to do it now - their agreement had said that they would not interfere with Materia unless absolutely neccessary, and in the eyes of many, the time had come now. Taking charge in this operation, the archangel of fire Aesturex seized the Soul Forge for himself, breathing his fire into it and creating the flames of purgatory.

The purgatory flames would serve to cleanse souls not yet corrupted past their breaking point, extracting the corruption and allowing it to be dealt with in a safer manner. Although that was far from the end of it - an afterlife for the souls had yet to be created, as well as a place for the demonic essence to flow to - after all, if it just remained in Materia it would not only corrupt the souls there, but also form demons of its own. Additionally, the beasts already born still remained, and one of them had already risen to such a level of power that it was clear that it would be the one to consume all others and then become the Beast Of Souls.

((Note for later reference: I had planned that the Proto-Beast / Beast of Souls / whatever (unfinished world ending monster) would be sealed somewhere between the planes, but that, even confined as it is, it's power is still enough to cause tears in reality and allow demons from the hells to escape into Materia. The souls of this beast and the other demons would be semi-indestructible, as Aesturex fears that introducing them to the Soul Forge could corrupt it, and Mors displays no interest in uncreating them, even when pleaded to do so by the angels.

I'm also toying with the idea of having a full-blown war of sorts break out between the beasts and humanity (with the assistance of the angels). The beasts would be immensely powerful and, after being struck down, self-reviving even, forcing humanity into a losing battle with the angels only being able to stall for time - furthermore, the angels would be unable to launch attacks too great in power, as that would end fatally for the remaining humans, resulting in even more demons being unleashed.

I had also planned that demonic essence, just like the first demons, couldn't truly be destroyed. It could, however, be used in a manner similar to mana, and, for that purpose, Heirir was established, where the souls of mortals would slowly take in demonic essence until they reached their cap (a soft cap, as the hard cap would have them turn into mindless beasts / feral demons) and, with the fighting focused nature of Heirir, they would use up the essence in displays of their power, easing the worries of the divines.

Although perhaps I could just say that, while it is possible to destroy demonic essence (by neutralizing it with mana used by a divine, or perhaps divine essence, should I make something like that up). In general, I will need to think about how divine magic is effective against demonic magic and vice versa. Currently divine magic is especially "pure" because it is extremely efficient, and divine souls are not corrupted, while demonic magic is the opposite of it, and mortal magic lies somewhere inbetween.))