Forced to Abdicate from the Start, I Summon Gods and Demons from All Realms

After transmigrating to a fantasy world, Xu Jinnian becomes the useless emperor of the Great Xia Dynasty. The Prince of Han, Xu Guan, forces him into a corner, but just then, Xu Jinnian obtains the Emperor Summoning System. From the start, he signs in and summons legendary generals from throughout history, including the God of War Lü Fengxian, the Hegemon Xiang Yu, and the Flying General Li Guang. He also summons divine beings and demons from across the heavens, including Nie Feng, Bu Jingyun, Di Shitian, Dongfang Bubai, Feng Qingyang, Lü Dongbin, and Sun Wukong. Xu Jinnian has the Prince of Han, Xu Guan, imprisoned in the Imperial Clan Court. Five days later, the Prince of Yan openly rebels with an army of a hundred thousand. Just then, Xu Jinnian discovers a message from the late emperor inside the Azure Dragon Divine Scepter he left behind: The eldest prince is the reincarnation of a Great Demon God, the second prince is the reincarnation of the Heavenly Emperor, the third prince is the reincarnation of the Moon Venerable, and the fourth princess is the reincarnation of a Female Emperor... Three months later, several princes and princesses openly rebel as well...