Activating Sunshot Divine Cannon required the jade plate in Qin Mu's hand. Since the battery was too large, it wasn't easy to control, so Qin Mu had created a tool to interact with it. The jade plate could then have the huge divine cannon shoot wherever he pointed.
It was the central control of Sunshot Divine Cannon.
Qin Mu taught Emperor Yanfeng how to use the jade plate, which was simple to learn and use. As a great master in forging, Qin Mu could simplify the most complicated things, and with just this point, he surpassed other great masters of forging by leaps and bounds.
Emperor Yanfeng put away the circular plate. After a while, he took it out to play with it before putting it back again. Some time later, he took it out once more to fiddle with it again.
Qin Mu said kindly, "Your Majesty can try firing one shot."