The Beyond is an undiscoverable realm (or realms) beyond all of reality and non-reality. It is beyond the outerverse, beyond the adverse, beyond the cosmos, and beyond oblivion. The Beyonders protect entry into this realm. What lies beyond is unknown and unknowable, except for concepts passed on to lower level beings.
There is a Gate at the edge of Beyond, which can only be opened by a Key. The Gate is the entrance to a Citadel which is protected by a class of Beyonders as well as unfathomable dimensional thought-magic that redirects all who approach.
The Citadel and Pyramid are presented as impossible dimensions, as they are thought constructs. If they are seen by lower level beings, they will appear impossible and improbable. The Beyond exists as an infinitely repeating series of thought projections overseen by the Eye which pervades over all at the apex of the Pyramid. All Beyonders are privy to an impossibly complex thought network which originates from and is enforced by the Brain.