What Nero didn't know was that while he was horrified by Pei Yan's abilities, Pei Yan was equally wary of Nero's fully manifested Body Refining Technique. Through data analysis, Pei Yan realized that if he engaged in a prolonged battle with Nero in such a state, he would likely be at a disadvantage. Although he might still achieve ultimate victory in the end, the time for the match to conclude would be significantly delayed, which was not what Pei Yan wanted to see. Therefore, scaring him away was the best option for Pei Yan at the moment.
