The One Qi Transforms into Three Pure Ones Technique was Dao Immortal's ultimate art. Because of its harsh cultivation requirements, ordinary people could never master it. Thus, after Dao Immortal ascended, this ultimate art vanished from the cultivation world.
Although Dao Immortal's disciples had been fortunate enough to study this technique, they could only grasp a fraction of its true essence and were unable to truly cultivate it.
Black Emperor was one of Dao Immortal's disciples, though not a direct disciple. He had merely been a child Dao Immortal took in while traveling across the continent. After teaching him for a time and leaving behind some inheritances, Dao Immortal departed. Black Emperor did not even know the identity of the cultivator who had once taught him.
This was also why the Dao Sect enjoyed such renown in the cultivation world today and possessed such a vast lineage. Back then, Dao Immortal had taught far too many disciples—so many that even he himself could not remember them all. After his ascension, everyone who had received his guidance considered themselves Dao Immortal's disciples. As a result, numerous Dao lineages existed in the cultivation world today. Aside from the Three Pure Ones Sect, there were many other inheritances left by Dao Immortal.
When Lin Chuan claimed that he could destroy all of Black Emperor's clones in a single breath, Dao Immortal was the first person Black Emperor thought of. His Clone Technique had evolved from the One Qi Transforms into Three Pure Ones Technique, and only that technique could suppress his clones so absolutely, destroying every one of them with a single move.
That was why he agreed to Lin Chuan's wager. If Lin Chuan won, it would prove that he truly was Dao Immortal's successor, and Black Emperor could no longer attack