Monthenia was known to be a substance that was considered the weakness of beasts and not only that, the substance hated beasts. However, this substance was able to take on the shape or form of other objects, as well as having two forms - one of a mere substance and that of a horrendous creature.
Demons existed. Beasts existed. Other distinct creatures existed.
And there was Monthenia - a substance whose true origin was yet to be discovered.
"Brother."
It was then that Arthur transformed into an upgraded version of the spikey being - Ereon.
Somehow, the dark vines on Max's arm spread to other parts of his body and soon, the purple-eyed boy's appearance was replaced by an equally spikey being and the sword that had been in his hand disappeared into his body.