Unlike other 'Dragon' techniques, this one will not stop unless it collides with a technique of equal or greater power, is stopped by you, or hits its target. It will plow through a mountain if necessary. Again, this skill requires an extreme amount of chakra since it is so powerful. It also requires a lot of concentration. This may be classified as a Darkness technique, but Demon Skills often combine two or more elements. Blackfire Dragon is Darkness and Fire, and since the shape and movement of Fire is inherantly random and eratic, you have to control it and form it into the shape of a dragon.