Sky Demon Energy. It was the ominous terrifying energy that had been stored within the Sky Demon Sword for ages. It had been now stored within Yeowun's internal energy, but acted as if it was alive and had a will of its own. It was vicious and destructive unlike other energies. This was why Yeowun rarely unleashed them except when he really needed it.
Yeowun thought the energy would only expand his own energy, but it was actually an eater. It tried to eat gregariously on the yin qi that came into Yeowun's body, even when it was the opposite type of energy. Yeowun had to send out the yang qi he had in his body in order to control the yin qi that his Sky Demon Energy absorbed, but the infinite amount of yin qi made him lose balance.
After the blockage was opened, Wang Yogun passed out.
'There we go! Argh!'