What Zhou Tian feared was that these NPCs might have other plans. Under these NPCs' machinations, he could run into some troubles.
Fortunately, based on the current situation, Zhou Tian could basically confirm that these NPCs indeed deployed their combat power to the territories of the other two monsters, just as they had indicated. Given this, Zhou Tian expected that it wouldn't be difficult to obliterate all the NPCs in his territory, as he had planned.
In fact, upon discerning the status of the NPCs, Zhou Tian then immediately initiated his planned actions.
The reason Zhou Tian accompanied his army into battle was not that he truly wished to participate in the conflict, but rather to guard against potential elite NPCs. Knowing that the NPCs not only hadn't dispatched any elites but had instead transferred their own elites out of their territory, Zhou Tian became wholly confident when dealing with those NPCs.