The Fungal Expanse

There, at the gateway to the darkened expanse that is the Illithid city Drl'kullatihk, lies an almost endless field of fungi. So endless, in fact, that it is its mere expansive nature that drew its common name. It is not uncommon for the Illithid to have their cities surrounded by the protective spores of some of the myriad of perpetually deadly fungus that roots within the Underdark but there is something about the Expanse that makes it unique, the very veins of magic that channel through this area gives the fungus a truly unearthly glow, iridescent and at times, blinding amongst the blackness of the Illithid interior. But mixed in with the clouds of toxic spores and the free flowing magic is the ever present influence of the Illithid Elder Brain, seeking any sentience it can grasp its tendrils around and indeed, the nature of the fungus and the corruption of the Underdark seeps into the expanse giving rise to almost mindless spore husks that surround the city and inhabit the expanse. Fungal drones, driven by the command of the Elder Brain to protect the city from all comers.

Of course the beauty of the Expanse can not be denied, after weeks of travelling through the Underdark to be met with a rainbow of colours reflecting off the mithril rich ceiling of the cavernous maw of the chamber, one would almost be forgiven for being momentarily distracted as you take your first steps within the fungal forests, that is until the fungal drones come upon with an eerie stillness, forcibly choking spores down your resisting gullet, if the act itself does not suffocate you then you'll wish it did, as mere hours after the occurrence the fungal spores will erupt from beneath your flesh and consume your mind, making you into yet another of the countless husks that serve the Elder Brain.

I imagine this being in the lower Underdark, and that it has been around for longer than the Illithid city was set up. Indeed I like the idea that it may even be possible that the Elder Brain has been somewhat affected by long exposure to the spores and may itself be a part of the expanse. Think "The Last of Us" but with Illithid. - Andywmason