Based on years of repeated raids and probing experience, every time the light array cuts down hundreds of Nascent Soul level great demons, while the Demon King level monsters don't even need to take action. As long as the lesser demons and the soldiers of Mo Zhu Mountain hold out until evening, Mo Zhu Mountain naturally has to retreat to rest, and the mountain peaks and cave residences taken during the day can be reclaimed overnight.
Actually, Mo Zhu Mountain also knows that until the Senior Disciples are free, there's no real chance of taking down the old lion; it's just routine training, bringing newcomers to experience the demon battlefield, earn some materials and military merit.
Zheng Zetian is such a 'newcomer.' He also donned a set of standard iron armor, following along with Li Shisheng on a ship, swaggering across the Floating Jade Mountain range, observing the demon nests from above.
