CHAPTER 177: End of the Battle
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What Hu Xingyan was using was clearly a simplified version of the basic spirit-Qi refinement technique that Ethan had used during his match against Xun Wei.
This was a technique not well known among adept and apprentice-level alchemists because, due to its high level of difficulty, it was practically impossible for them to use.
It was also challenging for expert, and master-level alchemists, who, although they could use it, applied it only to a limited extent.
Many didn't use it at all because they found they were faster refining without it than with it, due to the fact that two fundamental prerequisites were needed to master the technique:
first, having a cultivation level of at least mid-stage Qi Refining; and second, practicing it continuously, not for days, weeks, or months, but for several years.