Complete all 3 targets in the Yellow Turban rebellion. Start out by descending to the central base, once you've defeated all officers there head northwest and take the base that allows you to access the stairs up the walls. Go up the stairs, and follow the walls around to the first Altar and the general guarding it. Destroy the altar, kill the generals present. From here, go north and around the enemy main camp to the east, then south to the second altar. Climb the structure, destroy the altar. Head slightly east to kill the second required general in the Fire Trap area. Head toward the enemy main camp, killing any enemy generals you see along the way. Ensure that the two required allied generals are in the enemy main camp and finish the level. Be aware that Zhang Jiao's special attack can kill your allied generals VERY quickly, so I suggest an interim save before the last step.