Regardless of whether they sought to showcase their strength in an attempt to erase the negative impact caused by their previous performance, or to vent their original fears, the guild masters, with their abilities, were now presenting considerable pressure upon the NPCs by putting their full strength into action.
With only the defensive weapons within the city, it wasn't a problem for them to fend off one or two attacks from Zhou Tian and his guild masters. However, under the continuous, relentless assaults of several guild masters, the city's defensive weapons eventually couldn't keep up. And as a result, after exhausting their energy to resist Zhou Tian's too-strong attacks, the NPCs' last line of defense was torn apart by them.
Consequently, once Zhou Tian and his associates had destroyed the city's defense weaponry, no more surprises happened in the battle afterwards.