The world scene bone, divided into four grades. The first grade, heavenly spirit bone. Second grade, golden spirit bone. Third grade, Xuan Ling bone. Fourth grade, white spirit bone. The rest, all mortal bone. A mortal bone Xu Taiping, vowed to prove like this cultivation world, mortal bone can also be able to kill demons, mortal bone can also get rid of demons, mortal bone can also ascend