Duan Ling Tian had delayed going to the Three Great Sacred Realms to spar with Ku Mu's great-great-grandson.
According to Ku Mu and Han Wang, Ku Mu's great-great-grandson had grown arrogant due to his talent. Even Ku Mu was helpless against his great-great-grandson. He even felt that Ku Mu did not achieve as much as he did when Ku Mu was his age and that he would definitely surpass Ku Mu in the future.
Based on what he had heard, Duan Ling Tian already knew that the other party was arrogant and felt that he was above his peers because his peers were inferior to him.
