Really Like the Middle Ages

With the lessons left behind by defeat after defeat, the Kerrigans, known as the demons, learned from the painful experience and began to build their own emerging technological and industrial power with Tiber crystal as the core. However, those forces that had defeated the demons, including the human race, were intoxicated with their past glory and fell into a state of self-imposed stagnation. Therefore, when will everyone discover the little secret of the demon Cregans?