Sebastian's ultimate war vessel was OP.
Compared to his Atlantian body and even his main Megalodon body, this Leviathon body was the strongest vessel that Sebastian's soul has ever inhibited.
The mighty dominating power of Sebastian's new body was not because it was a Space Beast, even for a Space Beast, such power being packed inside a single body at the mere purple tier realm was an abnormality of the highest level.
Sebastian's ultimate war vessel was a product of extreme imagination. The body was that OP because of all the ideas that Sebastian realized in it.
Sebastian's ultimate war vessel came about not just from his increased origin law comprehension, but from the combination of his Mana Lord evolution route, the Red tier organs that he implanted on it, and his bonded Celestial Beast.