Xia Hong's shock was not without reason.
After achieving the perfect skin in the Earth-digging Realm, breaking through to the Cold Resistance Level only requires stimulating the blood and flesh beneath the skin with the medicinal power of the Yangyuan Pill. Though this breakthrough process is not without difficulty, the difficulty is generally within the range of human endurance, and the level of difficulty is directly related to the quality of one's battle body talent.
In other words, the better the battle body talent, the greater the pain endured, the more resources consumed, and the greater the difficulty of the breakthrough; conversely, the poorer the battle body talent, the less challenging it is. Those with the most ordinary Cold Resistance Level, with only 1 zag of strength after the breakthrough, have little difficulty besides enduring the pain of blood and flesh reorganization;
However, breaking through to the Xianyang Level is a completely different matter.
