Like all three generators, it was sent roughly 20 years before Ultima VII, just after the founding of the Fellowship. The effect of the Cube Generator is, that it emulates the Guardian's voice, speaking to the people in their sleep or when they are awake, telling them the things he wants them to believe and how good the Fellowship is (the Fellowship calls it their inner voice). It charms the people into joining the Fellowship. It is located on the island of the Fellowship.
The Avatar was told of the Generator by the Time Lord after the destruction of the Sphere Generator. But even going near it was painful, so after consulting the Time Lord and getting additional information from Moonglow, the Avatar went to Ambrosia to get Caddellite. Having made helmets of that metal, the noise became harmless (the metal covered the ears and filtered the noise). Inside, the Avatar solved the complicated puzzle, destroying the last of the Guardian's generators. This also gave the Avatar possession of the small Prism inside.
Having obtained the smaller Cube from inside the generator, the Avatar was able to hear the truth from the leaders/members of Fellowship with it. But it didn't work on Batlin who detected what Avatar was going to do and teleported away.
The Generator has two defense mechanisms:
- The Generator produces a hurtful noise that kills everyone coming too near. This can be countered by wearing Caddellite Helms (all members of the group).
- The inside of the Generator is a very dangerous Labyrinth of bridges, fire fields and traps, with many false leads.