Dark Hadou

The Dark Hadou is a form of ki that emanates greatly from oneself through the darker aspects of the natural human instincts, including the desire to survive, trample, and impose over opposition, and on a metaphysical level, the natural occurrence and manifestation of lose, decline, and destruction.

To tap into the Dark Hadou, a person must be so consumed with the desire for success and perfection, or have such an intense rage and hatred, that they are actually willing to destroy, as such, only people who push themselves to be the best at all costs can take full advantage of it, however, the untrained mind can be driven into a temporary insanity if one has not prepared for it. Learning the Dark Hadou is the first step in learning the most dangerous technique in their art, the Raging Demon.

Taken from Wikipedia.