"Iron Mountain Skill" can only be cultivated to the Seventh Grade Bone Forging Realm. To advance to the Middle Third Grades, one must cultivate martial arts that condense Qi-Blood, but all Blood Coagulation Martial Arts are monopolized by aristocratic families and are completely inaccessible externally.
After Zhong Lin advanced to the Seventh Grade Bone Forging Realm, the effect of cultivating "Iron Mountain Skill" became negligible, and he specifically sought out Old Zhou for advice.
As Old Zhou explained, martial arts cultivation involves externally training muscles, bones, and skin, while internally cultivating a breath.
Now that muscles, bones, and skin have been tempered, the next step is the transition from external to internal, tempering the internal organs.
However, the internal organs cannot be tempered directly like muscles, bones, and skin, as they are fragile and can suffer hidden injuries if not careful, so a special power is needed to strengthen them.
