After settling on heaven-and-earth root as the core ingredient of the Spirit Root Pill, Luo Chen selected thirteen other herbs, including Nightfeather Flower and Purple Sovereign Leaf, as the supplementary ingredients. In addition, he prepared a few more herbs that could be used as alternative ingredients if necessary.

Although thirteen auxiliary ingredients might sound excessive, the formula was actually quite restrained. In Luo Chen's view, Heaven Refiner's idea was certainly ambitious, but it was ultimately meant for mortals who had never stepped onto the path of cultivation. Because of that, the Spirit Root Pill could not be too high-tier. Otherwise, mortals would never survive its medicinal potency. Since the heaven-and-earth root had been chosen as the foundation, there was no need for multiple primary ingredients. That approach was common in third and fourth-tier pills, but low-tier pills generally relied on a single core ingredient supported by a few supplementary ones. In this case, the supplementary ingredients only needed to enhance the heaven-and-earth root's strengths while offsetting its weaknesses.

With that principle established, Luo Chen began refining the formula. There were a lot of possible combinations to play around with, enough that even a fourth-tier apothecary would proceed cautiously. Fortunately, the overall direction was already clear. What remained was to test, adjust, and refine the formula until every ingredient complemented the others perfectly.

Luo Chen traveled tirelessly between the three mountains and five lakes. His herb basket filled and emptied time and again as he gathered every medicinal ingredient he needed. The work was repetitive, but far from dull. Each herb he collected deepened his understanding of medicinal principles,...