Back then, the reason Demon King Liu failed was not that he wasn't strong enough or lacked preparation, but rather that he could not gain the approval of the Heaven and Earth Law. Because as a Snake, he lacked confidence in himself and sought to strengthen himself by transforming into a Dragon. Attempting Ascension with a Dragon's body not only led to his failure but became the very crux of his downfall. He was clearly a Snake, so why did he attempt Ascension as a Dragon? If he didn't even acknowledge his own bloodline, what right did he have to become a Rank Four Divine Spirit?
This was also why, after Demon King Liu failed his Ascension, an unwritten rule was established within the Snake Race: a Snake must not undergo Snake Becoming Dragon.
