From the moment Bai Zemin increased his natural Agility using his free Status Points to the moment Hero City's main weapon was triggered, no more than 2 seconds had passed. The brutal change in the battle situation made Bai Zemin himself unable to react, as for an instant his brain seemed to have short-circuited and stopped.
When the beam of white light appeared without warning, he finally understood what was happening.
Before beginning the battle against these Higher Existences, Bai Zemin had given both Shangguan Bing Xue and Wu Yijun a Spiritual Record Stone containing his blood and part of his records. Although it was impossible for both women to control the entire city with this Spiritual Record Stone, it was no problem to let them control one or two functions for a short period of time.
Clearly, Wu Yijun or Shangguan Bing Xue activated Hero City's main and strongest weapon: the God & Demon Killing Tower.