Had it not been for Yun Ming, the power of the two Godkiller-ranked fixed soul ammunitions would have been enough to destroy all the shelters in Shrek. Yun Ming alone had endured almost half of the explosive power back then. If he wished to leave at the time, no other person would have been capable of stopping him. However, he could not because he was the Sea God's Pavilion Master. He was the protector of Shrek Academy.
The Holy Spirit Cult knew of this and chose to exploit it when they attacked. Their goal was to set a death trap for the number one man on the continent.
Under such circumstances, Yun Ming's soul had still survived and attached itself to his martial soul to prevent annihilation. This was the act of a man that was close to being a divine miracle.
Wu Zhangkong did not take part in the battle against Spirit Academy because he still needed to conduct the entrance examination for all of Shrek Academy.