Heavenly Demon Arts is a martial art that uses energy called Ki, also known as Chi, Qi or Prana. Heavenly Demon Arts have unique way of controlling the flow of Ki, per Noyas teachings there are three basics to master the control of the flow; breathing correctly, walking correctly and sleeping correctly. Through these core practices, and a variety of physical and spiritual techniques, users of the Heavenly Demon Arts can manifest great power in combat and reach abilities far beyond normal humans.
If a practitioner overexerts themselves, expending too much Ki too quickly, they can suffer internal damage to their bodies as backlash. If one were to completely use up all their Ki they would die.