For this one you will have to go to Battle of Chang San, on Yuan Shao's team. First go to one side of the castle(the side were Lu Bu get's ambushed.) Then keep killing the Guard captain's troops(the one near the west entrance to Chang San castle. Then keep killing the troops there that come out of the gate. Note: Don't kill the gate captain.If you do kill him then go to the other side where the other Guard Captain is. The precious item report is at the middle of the castle courtyard.