Boom!
The power of Grotto-Heaven Masters erupted, and monstrous airwaves sent countless demonic beasts flying.
The six Grotto-Heaven Masters were like a reliable Great Wall, blocking the demonic beast army outside the human continent.
It had to be said that the six Grotto-Heaven Masters were comparable to an army of a million humans, and the effect was even better.
If they had stepped out earlier, the human race wouldn't have experienced so many hardships.
Of course, this was mainly because the Demon Realm didn't expect human Grotto-Heaven Masters to attack so directly. Otherwise, the Demon Emperor of the Demon Realm wouldn't sit back and do nothing.
Under normal circumstances, Demon Emperors and Grotto-Heaven Masters only existed as deterrence forces. It was actually very rare for them to fight.
After all, be it Demon Emperors or Grotto-Heaven Masters, they were pillars of their respective races and wouldn't take action easily.