The One Who Can Not Be Named. He who rules many worlds. He whose Name is not meant for our ears, but who is known in all worlds as EVIL...
As we can see in Dungeon at the Heart of Dawn, the only way to attract the direct attention and intervention of the Nameless One is to go into the Tower of Darkness - named thus because of its lack of windows - and somehow find the Box of Balefire.
If the lucky finder is then somehow stupid enough to open the Box, it spits out a bar of whitehot fire, which shoots up into the sky. A strange, growl-like noise is heard from within the Box once its lock has been removed, and this sound increases in volume as the light shines out.
Within a few moments, the sky becomes overcast, a storm builds... and the NO appears.
Weīve only seen him in the shape of a column of whitehot flame, surrounded by yellow lightnings, with a snakelike body of green flame above the stormcloud-line, all topped by a really ugly face, but since heīs so mega-powerful, he must be able to take on other forms.
The NOīs power is demonstrated first by the fact that all is destroyed in his wake in the shape mentioned above.
Second, he was able to destroy a castle of Venger's and overpower both Venger and Dungeon Master, even when the latter was using the Weapons of Power as an extra boost to his own magic.
Third, anyone who sees his face - he reveals this before spitting out deadly flame - is going to lose.
And finally, he is able to teleport his not inconsiderable bulk around whatever world heīs on with surprising speed; Dungeon Master couldnīt stay ahead of him for long. You just canīt shake this old evil within a world - only if you start dimension-hopping can you escape.
The NO is a conqueror and ruler of many worlds, but always wants more. According to Venger, he is Vengerīs Master, and wants to rule the Realm. He left Venger certain instructions a long time ago before leaving him; Destroy Dungeon Master. Conquer the Realm.
When it turned out that Venger hadnīt succeeded, he proceeded to wipe his servant out. Fortunately for Venger, he managed to beat it to another dimension, and his Master didnīt follow after.
It is unknown whether Venger had tried to save his relationship with the arch evil, but it seems clear that his great powers either do not stem from the NO, or were a permanent gift. Once Vengerīs energies were restored, he seemed none the worse for wear.
It is unknown when Venger and the NO first met, or why the NO approved of Venger as his right-handman in the Realm. He could have just raised an army or stomped out the resistance himself.
This perhaps indicates that the NO isnīt comfortable being inside any one world at a time. Maybe he has relatives out to take over his universes, and has to be on guard?
Perhaps the alien energies of the NO (if this guy ainīt alien, I donīt know what is) for all their greatness, degrade once inside the Realm. There could be something specific keeping the NO from walking around as he pleases. Maybe thereīs just too much goodness in the Realm still?
M.H. Bartels