Yun Yanli's Kung Fu was at the level of a Great Deity. In order to test out his strength, he once snuck into heaven and challenged the Great Deities anonymously. He had faced all of them, except Shen Jiuli, Ning Xueno, and the current Emperor Immortal. The result was satisfactory to him as he had defeated all of the ones he challenged. No one was able to beat him, not even the Lords who had ascended from the Earth.
Back then, he was worried that his cover might be blown, so every ambush was a quick one. He attacked, he fought, he won, and he left. As for those Great Deities who had unfortunately been defeated, they were too embarrassed to admit defeat and decided not to mention a word about the incident. Therefore, Yun Yanli was never quite fully satisfied with his victories, as no one knew who the mysterious man actually was.