Total Flow is an ability used by those who practice the Art of the Legendary Nox Warriors. It's a key concept in the Total Flow series. It enables the individual access to the "Total Flow State", where the Aura of the individual becomes strong enough to give him/her the superpowers which are determined by the fighting style. The series is named after the ability. There is a variant of this ability used often by common people (apart of descendants of Nox) called Partial Flow.
The characteristic "glow" of the combatant's Skin Marks (which are like "tattoos" and eyes during this state is due to their role as a ventilation mechanism, like that of a computer. In that way, the side with more of these "tattoos" will work best than the other side, and the individual will soon become exhaust if the Aura becomes too strong and overpowers.
A common side effect on some people is the supression of nearly all emotions upon reaching the state. That side effect can be reverted if the affected person exits the state by lowering the Aura to its common minimum.