The Luxolhan
"Just one more reason, to not trust the C'tans."
"Hihi! I'm Meikyu!"
The Luxolhan, or the Book of Infinite Spiral, is a sentient magic item which has, as of lately, projected it's own physical form in the shape of a abyssal spirit like entity. They have ominiously hinted that when they sing they have the power to 'raise armies of undead'. However, for whatever reason, this powerful entity said... That it wants to try living. And being a better person. With not even their closest companion, Riqueza, knowing what sparked that change in such a clearly volatile entities personality. The thought that such a creature was not good before can only mean so much. They don't often use their powers outside of extremely simple ones. Meikyu has made clear several times that this is just their humanoid form, and that their 'core' or 'actual self' is a very ominous looking book. But their true sentience and power comes from the Demiurge's eye.
How the crafter of said book, the Unknown, got into possession of the eye seems to be that they were a direct cleric to the Demiurge, and as of being a goddess of knowledge, she sought out to seek what is past the great barrier. Seemingly recognizing and oddly respecting this autohrity, the Demiurge removed one of it's thirteen eyes, and gave it as a holy artifact down to its cleric, which she proceeded to then make into a unholy book of massive power. When finally she learned by reading the contents of the book what lays beyond, she calmly set down the book, and proceeded to leave her lonely station to instead go experience the life she was wasting looking for hidden information.
Meikyu was deeply effected by this experience, and whatever sentience lay in the eye became more 'human' you could say. Seeking as well to explore the world and see why exactly that was the Unknown's response to her repitore of forbidden knowledge. However through history, owners of the Luxolahn have been corrupted, using the powers of the book, which she will willingly give over, to destroy entire worlds in death and necromantic like abilities.
The Demiurge from time to time is known to find Meikyu again, in smaller avatar like forms, and decorporalize their physical form. Taking the eye, and impaling it on a claw in the pupil, in order to cipher information from it. Before removing the claw and allowing it to reform. So far, it has just simply chosen to not take the eye back. It hides it's missing eye with its head wings.
The truth behind the Luxolhan is that it is a artifact that absorbs negative energy, or energy that would drive one insane. It is an item from Steelport, the titular place of where all of this started. It was blessed by the Ars Goetia and Sans Angerium to be Elias (Or The Demiurge's divine artifact.) However, it served a second use of being a 'Kill Switch' to the Philospher Stone if wielded by a C'tan. While it is supposed to be a guide to the new world, it had the unfortunate honor of being within Elias' jacket when he was displaced with his Ego by the Rebis in order to complete the death march. However, he was abandoned there for he could not move without his Ego, to be directly within the eye of Shi, unprotected. His mind irreversibly shattered and overflooded with negative energy over and over again for a seemingly endless eternity, until he was pulled to the modern by Paimon. It is believed that the Demiurge sent innumerable amounts of it's worshippers deep within the dream, sacrificing them to retrieve the book from off of Elias, to which then the entity Erosyan blessed the object unto 'Unknown', a manifestation of the Abyss pillar whom worshipped him. From there, Erosyan blessed upon the Luxolhan one of it's 13 eyes. Eventually ending in the saving of Elias, which seemed to have been its plan in the long run. Meikyu continues to serve as the sentience of the book, wielding one of Erosyan's eyes, as a way to better protect it from hands whom should not have it. The amount of negative energy that the Luxolhan observed while being on Elias was limitless, which explains why it's song drives people insane when it sings, and has the power to destroy and collapse entire planes of reality. Elias, now manifested forward, alongside the aid of Roscoe spends most of their time attempting to decipher its maddening pages that have been altered and seared with Shi's influence to see if there's a way to harness the power of their very enemy.