Feng Nian uncovers the mastermind behind the 3 assassination attempts on his life, but realizes that he was never the intended target and the attempts were part of a larger scheme. Xu Xian is aware of the political maneuvering behind the scenes and uses this to his advantage, much to the disapproval of Feng Nian. Though given two choices to secure the line of succession goes to him, Feng Nian decides to choose neither, in favor of less bloodshed. (Source: frankly at MyDramaList)