Zeromus

Players can carry over all their items from their first playthrough, and stealing the item Dark Matter from Zeromus — the final boss of the game — unlocks a post-game dungeon with some of the hardest enemies and bosses in the entire game.

This miraculously works, and Zeromus is destroyed.

You are left to fight a creature called Zeromus, who is a manifestation of Zemus' hatred.

I am He who is called Zeromus..

In the moon's core, the party witnesses Golbez and Fusoya kill Zemus, but then quickly fall to his resurrected form, the spirit Zeromus, the embodiment of all of Zemus' hatred and rage.

Zeromus: I am the wellspring of darkness, fed by Zemus's unbridled hate.