Refers to Taoism, the ability to change and manipulate ghosts and gods.
According to Baidu Encyclopedia, Xuanhuang: the color of heaven and earth. Xuan is the color of the sky and yellow is the color of the earth. "Tianxuan Dihuang" comes from "Yi Kun": "On the sixth chapter, dragons fight in the wild, and their blood is black and yellow." The ancients respected heaven and earth, so they used heaven and earth as a symbol of eternity and mystery, so they used "Tianxuan Dihuang" as a symbol of eternity and mystery. The vast sky and vast earth are synonymous with each other, and are also commonly used in traditional Chinese medicine to understand qi and blood.