Bad Guy: After Sleeping for Three Hundred Years, He Becomes Invincible When He Comes Out of Seclusion.

During the Taizong period of the Tang Dynasty, there was a killer who eradicated dissidents for Taizong before Yuan Tiangang. After Taizong ascended the throne, he was given the surname Li. However, Li Xuantian refused to become an official. Just as Yuan Tiangang proposed that the Tang Dynasty would be destroyed, Li Xuantian volunteered to step into the bottom of the Cave of Ten Thousand Corpses and sleep for three hundred years before reviving the Tang Dynasty. The night before his sleep, Taizong secretly met with Li Xuantian. No one knows the content of the secret conversation that day, only Li Xuantian, who has been sleeping for three hundred years, knows.