TDG: Transmigrated with knowledge of a Supreme Expert (fanfic)

Tales of Demons and Gods reader finds himself transmigrated in the body of Lin Tian, a commoner student and reincarnation of an expert from ancient times - another user of the Temporal Demon Spirit Book! With the knowledge and abilities of a supreme expert not any inferior to Nie Li, Lin Tian sets out on his own path to the peak, aiming to make the best use of his knowledge of the novel that he was gifted with! Just a note: the MC is not a villain, but close to it. He's quite morally gray.