Li Er: What Does It Mean for the Prince to Give Way to Me on His Own Initiative?

Li Zicheng travels back to Li Jiancheng, the crown prince of the Tang Dynasty who lived in the ninth year of Wude. What does it mean that Li Shimin secretly reported himself to cause trouble in the court? What does it mean that I am hosting a banquet in the East Palace tonight? What is dove killing? Li Zicheng felt like the sky was falling, no, God, are you kidding me?