The "Earth or Ground" form, this one is one of the most powerful of these Qi disruptive katas having two very powerful qigong methods along with some extremely dangerous self defense methods.
This kata teaches how we use every movement, no matter how small to set up teach following movement in a free-flowing, but illogical fighting method. Illogical? Yes, because that's how fighting happens, you cannot use a logical martial art for street fighting.