Zhou Tian did not participate in the combat. With his strength, had he been willing to fight, the pressure on the monsters under his command would have definitely been reduced significantly. However, due to other considerations, Zhou Tian ultimately abandoned the idea of getting involved in warfare.
The NPCs had already begun to fight desperately, and because of their performance, many players were now attracted to join the battle situation. With the addition of those players, the NPC army, whose combat power should have been far inferior to Zhou Tian's monster army, managed to persist and even gain some advantage on the battlefield.