Long Xingyuan and his team had been conducting research on how to achieve Demon Promotion, proposing many theories.
One Fusion method would be to continuously vie for authority with the Great Demon before its will had even formed, slowly integrating with it, and thereby completing the Demon Promotion. This method was undoubtedly the most secure.
First, there was no need to confront a formidable adversary such as a Fifth-order Great Demon, and second, with a strong enough will and sufficient time, those of Fourth Order Superior might also be able to achieve Demon Promotion and ascend to Fifth-order in one fell swoop.
However, such a method required not days but years, several years even, and no one could guarantee who would progress faster in this process.