Hell Guardians.
There were a total of 7 of them in number.
Each of them carries powers beyond what mortals can even imagine. Even the Gods didn't dare to interfere with them, and left them in their own domains.
Though with great powers comes limitations of equal level.
Each guardian was tasked with protecting a part of the Hall Prison in order to prevent the escape of the imprisoned ones.
And that bound them to the part they were supposed to protect. In a limited area, from where they could never escape, despite having the powers to destroy the hell itself.
As once mentioned by a certain top player who ventured hell, the guardians are bound with rules and regulations that they can never break free from. As long as you follow the rules, none of the guardians can even touch you, let alone kill you.
In all honesty, I have only seen one Hell Guardian, Duraral. The Giant Demon, who protected the gates of the 4th Hell.
