Xu Yi's interest was piqued. It was simply the interest of a master of numerology in a difficult problem.
As for the Hun Tian Sword, it was also a difficult problem in his eyes.
Ever since the Green Demon King had given him pointers that day, and he had cultivated the Hun Tian Sword with three Domain Sources, he had been unable to break through to its highest level—four Domain Sources.
Xu Yi was so fixated on the fourth Domain Source because, after completing the exchange of his spiritual energy, he had once used the Hun Tian Sword to produce four Domain Sources. They had vanished in an instant.
That proved the Hun Tian Sword was capable of producing a fourth Domain Source.
The reason he had yet to succeed lay in the fact that the edifice of his numerological model had not yet reached a state of perfect unity.
Of course, Xu Yi still prioritized his cultivation of these two techniques.
Light Smoke Steps was an escape art he urgently needed at the moment, so he had devoted the most thought and effort to it. His progress had also been the most significant. Xu Yi believed it would not be long before he finished building the entire framework of Light Smoke Steps.
Aside from researching techniques, he had also read his fair share of all sorts of classics and notes. These covered cultivation records, methods for harming others, anecdotes and oddities, and even strange tales about geography. They contained a little of everything, and he read it all.
Second, he studied the medicinal properties of herbs.
His research mainly focused on the three ingredients used to refine the Origin Pill. He had spent a great deal of time on it, but made little progress.
He never missed a single