Perpetual motion machine.
Clearly, the Huai Guang Church is aware of this as well—their prototype was, after all, the Twins born during Heavenfall. Even by relying on Retrospective Vision, they could know all the details of that time.
Not to mention, Huai Guang and Dragon Island are in a cooperative relationship. Since the True Dragon could inform Ian of the existence of the perpetual motion machine, it would definitely also tell Huai Guang.
But on the other hand, as the native inhabitants, Huai Guang might have mastered more details about the perpetual motion machine.
"What exactly is going on with the perpetual motion machine?"
