The primary reason Zhou Tian waited until he evolved into a King-level BOSS to start his operation was that he had already anticipated meeting the kind of resistance he was currently facing if he launched a full-scale attack on other monsters.
In the past, Zhou Tian had no confidence that he could handle such a resistance. But now, with the power of his domain, dealing with those monsters had become significantly easier for him.
Ultimately, while allowing his Bearman Army to continue the current invasion operation, Zhou Tian himself went to the location of the Monster Alliance army without a word.
Zhou Tian's move immediately triggered a massive response from the Monster Allied Army.