Playing Yin and Yang

(This is a fan work based on Teacher Miao Qimiao's Thirteen Ghost Gates trilogy: Coffin of Life and Death, Borrowed Skin from the Yellow Springs, and I Come from the Yellow Springs.)

"One coffin holds the eight wilds at bay, half a life gambles with yin and yang. White lanterns light mountains and seas, evil souls knock at Heaven's gate." Hidden in this doggerel is a shocking secret...

A ghost rhyme about sorcerers from thirteen sects has suddenly begun circulating in the world of occult arts: "The road of yin and yang, the mouth of the Yellow Springs, the thirteen ghost gates guarded by the living. The lantern-bearing jailer, the Marquis in Brocade; the waystation of the dead, the mountain-watching dog. The Door Gods, the Water Immortal, the Confucius Temple; red lanterns and white funeral banners circle the streets; the yin-yang scouts stab Yanluo." This ghost rhyme had been lost for a long time. What does its sudden resurgence have to do with that poem?