Kaio-ken: (界かい王おう拳けん) Kaiōken is a technique. It multiplies the user's Ninjitsu Ninpo for a "heartbeat" and turns their aura crimson - amplifying their power and speed to overcome previously stronger foes at the cost of extreme bodily recoil. Strong mystic power control is required to wield the Kaio-ken properly.

When activating the Kaio-ken, the user gains a red and fiery aura, and in turn, their whole body and clothes acquire a reddish tint. The power of the aura also bristles the user's hair and clothes if they have any, the Kaio-ken must remain with its aura active all the time. There is no change to the user's physique, but the enormous stress of the technique can result in increased blood pressure, popping out veins, and swelling of the user's muscle mass. The technique can also generate large amounts of heat from the user's body whilst being activated, creating steam rising from their body.

As a result of the Kaio-ken, the user's base power level, strength, speed, and even sensory awareness greatly increase for an instant. With training, the length of activation can be increased, as shown during Nathan's extended use of the technique against Shendu or Zod; eventually, during the fight with Drago, Nathan manages to hold a casual conversation with the technique actively and uses it continuously during their next engagement. This change is quantified as doubling the user's power level for the base Kaio-ken technique. This short burst of power beyond the body's normal maximum output comes at the cost of increasing the flow of mystic energy within the user's body, taxing it, and requiring great skill and concentration to keep it under control. The uprise of power flowing inside could easily obliterate them, and even when kept under proper control still causes intense muscle spasms, pain, and weakness after prolonged use.

A/N: WE GOT THE KAIO-KEN!!! OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!