This Is Bad!
The fight seemed impossible to win, especially under such circumstances. And yet everyone fought bravely, showing great might and challenging any incoming enemies, stopping them all without losing much in return.
The high-end masters didn't hold back at anything, and used their strongest techniques when time needed to. They didn't focus on killing everything around them, just wounding them enough for the rest of the masters around to take them down.
Doing so made them free little time and effort, enough to sustain a faint balance between getting crushed or overly exhausted. As for William, he kept moving between the vast frontline, acting as a firefighter. He'd spot any place where things were going out of control, before heading towards and help masters there to sustain the pressure.
These occasions weren't rare, happened especially at the intervals between the formations he laid before. He used everything in his power, his monstrous and flying weapons, even his grenades.