The dean believed that he had obtained the truth. With this, he could explain why that water elemental Domain master had never left the scene — he had probably been killed by Mu Shui-qing right at that spot. And this was also why Mu Shui-qing clearly knew the opponent had been a water elemental Domain master.
Connecting the dots, the dean arrived at an answer. This would also explain why Lu Nan had been unable to lock on to the other two energy signatures. Think about it, how could a Domain stage person use their abilities across stages to track the movements of a God-Realm master? Perhaps at the very moment of locking on, this Old Beast had already noticed the trace, and had then given a slight warning by using mysterious means to destroy part of Lu Nan's energy.