C43 Big mystery

When Su Yuewu saw such unadorned and unadorned mechanisms, she asked, "Who was the one who made such an exquisite and natural mechanism?" Is it Elder Nan Gong? "

Bing-Er shook her head and said, "These books were all planted by Xue Yue. After fusing a few eight trigram formation techniques, it is easy for a normal person to touch the bell in the dark. The person inside will know