An hour after Acedia took William under the water's surface, the Half-Elf finally returned to the Thousand Beast Domain in order to handle the aftermath of fighting against Morax and the Giants that belonged to the army of destruction.
The timing of Morax's appearance was simply too perfect.
William had just finished conquering the Dungeon of Atlantis, and he was still under the fusion form with Sun Wukong. Because of this, he was able to fight against Morax, despite the fact that the latter was still stronger than him.
In the end, it was Ruyi Jingu Bang that tipped the scale to his favor. Sun Wukong's weapon was truly amazing, and its ability to pound beings below the realm of Godhood was truly outstanding.