Celestial Dragon Transformation Scripture
The four Jade Slips that the Azure Dragon God left for Xue Bai each correlated with one of the Great Realms, so after finding out which ones were which, Xue Bai first grabbed the Jade Slip that correlated with the Houtian Great Realm, and brought it to his forehead.
The Body Tempering Art that the Azure Dragon God left for Xue Bai was named the Celestial Dragon Transformation Scripture, which was something he had found in a Secret Realm during his youth. And after learning it, he soon started to rise from a normal youth in the extremely competitive Azure Draong race into the powerhouse that shook the Immortal World's Dragon Clans.
This was also why Xue Bai was so eager to learn its profoundness. It could make the Azure Dragon God trample all of his peers in the Immortal World, so imagine the advantage it could give Xue Bai in this primitive Baishen Plane. The anticipation was killing him.
