Skilled martial artists are capable of producing a battle aura, which is a manifestation of the user’s ki, spirit and often his emotional state. One who has produced a battle aura is wreathed in a glowering aura, which flows around him like fire. The exact color and form of this aura varies from person to person and can vary wildly with that person’s emotions. A martial artist must have a very strong willpower in order to manifest a battle aura and a lot of ki in order to maintain it for any length of time.
A battle aura exerts spiritual energy and can provide protection from other spiritual phenomenon, such as ki blasts from a martial artist or possession by a ghost. When the battle auras of two hostile martial artists meet, they clash and produce spiritual pressure between them. If one combatant is overwhelmingly more powerful than the other, he may be able to harm his opponent with this pressure alone. Some techniques, such as the Hiryu Shoten Ha, take advantage of this spiritual pressure in order to work.
The easiest way to produce an aura is to link it to an emotion, such as anger or depression, but emotion-based auras are more limited in their applications. By far the most common kind of battle aura is the “hot battle aura” – an aura powered by anger or determination and which gives off heat and strengthens the user’s body, increasing his strength, speed and/or toughness.
The Jigoku Waza is powered by distress and frustration this focuses the aura projecting it out as a distorted demonic version of user. This aura is used for inducing fear or intimidation, but with enough skill can also be used to physically attack.