One must understand that the more abundant and full the True Qi one manages to accumulate before breaking through to the Xiantian Realm, the greater the reinforcement of one's internal organs and extraordinary meridians at the very moment of stepping into Xiantian.
Moreover, it provides a certain opportunity for the physical body to become sturdier and more resilient against damage.
To a certain extent, compared to the Houtian Realm, the Xiantian Realm represents an essential, qualitative leap, as if the two are separated by an unfathomable abyss that is difficult to cross.
Chapter 30