The most powerful art was neither the Thunder Art of the Heavenly Master Sect, nor wasit the Elixir Brewing art from the Medicine God Valley Sect or the Ghost Reining art of the Ghost Witch Sect.
It was the art of casting Array Formations.
Array formations could tap in the source of energy inside of mountains or rivers to support itself. Since it was connected to the Power of Heaven and Earth, it was much more powerful than any individual. Legend has it that the brilliant strategist Kongmin of Shu Kingdom had stopped a hundred thousand strong army of Wu nation using an Array Formation during the three kingdom period. Although the effect of the array could have been exaggerated later by fictional portrayal, it was still a gleaming example of the Array formation's power.