The other type is zombie cultivation, which involves the transformation of corpse monsters. This is because heavenly beings possess celestial bones, with the bones integrating into the circulation. However, it is rare for zombies to cultivate the Undying Bone to perfection in the world; without achieving the integration of bones into the circulation, evolution into Drought Fiend can't be discussed.
From the moment Xu Qing began refining the first piece of Undying Bone, he had the opportunity to bypass the state of perfection and advance into the Flying Corpse realm.
The Flying Corpse is equivalent to an Immortal, yet will never achieve the realm of Kui Ba in this life.