Open the game, go to Cang Yue Island to find the fiend statue, click on the fiend statue and accept the fiend task.
According to the mission requirements, go to the misty forest, find the mysterious old man, and get the clues given by the mysterious old man after defeating the mysterious old man.
Go to the Red Moon Canyon, find the Red Moon Demon, and get clues from the Red Moon Demon after defeating the Red Moon Demon.
Go to Dayimen, find Master Dayimen, and get clues from Master Dayimen after defeating Master Dayimen.
Go to the Red Moon Canyon, find the Red Moon Devil, and get the mysterious ancient books after defeating the Red Moon Devil.
Go back to the game interface, click on the backpack, find the mysterious ancient books in the backpack and click Use.