Editing Darklord (section)

===5e===
5th edition has its own take on the idea. In a nutshell, the God-Brain hails from the era when the Illithid empire was at its peak, performing whatever blasphemous experiments took its fancy until it literally thought something that was unthinkable. That is, it had a thought so blasphemous, so utterly inimical to reality itself, that even an Elder Brain couldn't actually think it. Becoming obsessed with this ineffable thought, the God-Brain began cannibalizing other Elder Brains to try and upgrade itself to the point where it could finally contemplate this mysterious thought-form. Instead, it just gave itself kuru. Aghast at its behavior and terrified of catching the disease themselves, the other Elder Brains pooled their powers and tried to erase the God-Brain from existence; thanks to the meddling of the [[Dark Powers]], they only succeeded in banishing the God-Brain to the [[Demiplane of Dread]]. Now the God-Brain struggles endlessly to both find a cure for its disease and to manifest the alien thought-form still gestating inside of it, all the while subconsciously aware that there is '''nothing''' it can do to achieve either goal, but desperate to fight for every last moment of life.

In 5th edition at least, the God-Brain cannot fully close the borders like other Darklords do.  When the borders are closed, the surface of Bluetspur becomes covered in lightning storms and anybody who isn't an aberration that exits the domain both by above or below ground suddenly wakes ups in a familiar place with no memories of their time in Bluetspur.