Great Tang: Starting by Beheading Jieli and Rescuing Li Shimin

On the night of the full moon, Li Tang, the legitimate eldest son of the Tang dynasty, was attacked and thrown into the Wei River. Rescued by a reclusive master, he took the name Tang Tian. Nine years later, he returned with a divine beast and made his name in a battle on the banks of the Wei, slaying Jieli Khan and turning the tide for the Tang dynasty. He showed his compassion by providing porridge to refugees, and amazed the court with his bold arguments on state policy. When his true identity comes to light, how will he choose between family and duty, and protect the peace of the Tang dynasty?