Elysius

Elysius (uh-LEE-zee-us) is a being of incomprehensible might. He was introduced on August 24, 2020 and subsequently became a sort of boogeyman to Matthew, mentioned heavily but rarely seen. Matthew came to him seeking the release of Tetrad, who was apparently Elysius' prisoner for some time. Elysius agreed to release the Surreal Seven member, but one one condition. If GB, whom he called "Roundling", were to perish in the coming war, Elysius would subject Matthew to a most gruesome fate. Matthew agreed to these terms, and Elysius released Tetrad from his clutches.

Elysius' next appearance was in Void Manifesto, Pt. I, where he stalked Matthew and Melon as they fled across the cosmos.

Static Jack manifested Elysius' likeness in Void Manifesto, Pt. II to remind Matthew that he could not kill The Green Ball.

At the end of Bröthers in Entropy, Matthew imagined the defeat of his army at the hands of Elysius. He foresaw Melon and countless others being absorbed into Elysius' outer shell. Matthew chose to abandon his army following this premonition.

Finally, Elysius appeared after GB's suicide to harvest Matthew as promised. Matthew called upon the power of the Ancient Ones and took a Voidpill, but it wasn't enough. Elysius effortlessly pulled Matthew into his outer shell. When Matthew awakened in Elysium, Elysius explained that he would offer a slightly different punishment than the one originally described. He manifested the @all_hail_the_mat profile page, only it didn't have any posts or followers. Mat unrolled to reveal a large eye on his person, signifying his ascension to the meta. Elysius' next words were the final ones of the series — "Enjoy yourself, Almighty Mat."

Personality
Elysius is highly sadistic, but, for reasons unknown, he cannot practice this sadism freely; He is only permitted to intervene with the material world when a contract has been broken. Because of this, he ropes individuals into contracts he thinks they will break. This is presumably how Tetrad came to be in his custody. Elysius takes great pleasure in torture and cruelty. In addition to this, he seems to be aware of the meta. He has acolytes throughout the universe, such as the Green Ball, who worship him as a deity. This seems to earn them his favor. Elysius also has some kind of relationship with Papyron.

Abilities
Elysius can imprison people in his pocket dimension, Elysium, for extremely long periods of time. He can suck objects into himself, even a star at one point. He can also teleport between vast distances. He is impervious to physical damage, as evidenced by the futility of Matthew's final assault. Matthew once believed that the Cephaloid army could subdue Elysius, or at the very least serve as a barrier to forstall his own eventual reckoning. Elysius facilitated Matthew's ascension to the meta, citing a mysterious new agenda to which they were both beholden.