The Illithiad

A Walk Through the Planes – Part 54: The Illithiad & Dawn of the Overmind




It may seem like I only cover releases by Bruce Cordell and Monte Cook lately, but that’s just because of how big of a role they had in 1998’s planar releases. Cordell in particular had an odd role in the Planescape era; despite his actual writing for the setting being pretty limited, he still inserted planar content into much of what he wrote. This included his books focused on mind flayers for the final series of Monstrous Arcana releases, which began with The Illithiad, then continued with A Darkness Gathering, Masters of Eternal Night, and finally with Dawn of the Overmind. All of these releases came out in 1998, and while the earlier adventures were only short, 32-page affairs, the combination of all of this together is quite an epic undertaking that did a great job of redefining the role of mind flayers in D&D. It’s the strongest of the Monstrous Arcana series, though finding original hard copies of the books today is nearly a Planescape-collector-level difficult undertaking. 

As odd as it may sound circa 2022, in a fifth edition, post-Stranger Things world like the one we now live in, mind flayers used to be a somewhat obscure monster type, largely thought of as one of the many strange Spelljammer denizens. That’s AD&D‘s space-sorta-kinda setting, and it’s filled with plenty of unique monsters, many of whom are vaguely embarrassing. Shannon Appelcline notes that, “mind flayers became so important to Spelljammer, that TSR’s designers got flak from the marketing department when they tried to introduce them to the Ravenloft Campaign Setting (1990). The designers eventually had to prove that the monsters predated Spelljammer before they were allowed to include them in the new setting.” While they were a “unique” creation of TSR’s, owned by the company despite certain, umm, resemblances to other properties by a certain racist early 20th century horror author, it wasn’t until this series that they truly became ubiquitous. The Monstrous Arcana books put the spotlight on one iconic D&D monster a year, first the beholder, then the sahuagin, then the mind flayer, and did so in a prestige format, with gorgeous full-color splatbooks filled to the brim with the intricacies of each one of these creatures. The mind flayer series was unfortunately the last of these, but at least it was an excellent way for it to conclude.

I had to see it, so now you do too.

Most of The Illithiad is obviously not planar content, it’s only the origins and history of the mind flayer that Cordell connects them with the planes—in particular, he connects them with his own plane, The Far Realm, which he previously introduced in The Gates of Firestorm Peak.  Mind flayers were first depicted in the first issue of The Strategic Review, and soon afterward in the Eldritch Wizardry book for the original version of D&D, but other than their tentacles and ability to psionically mind blast enemies very little was explained about them. This changed with the first edition Monster Manual, which depicts them not as an extraplanar race, but rather as inhabitants of the underdark. It wasn’t until the October 1983 issue of Dragon (#78) that they were thought of as anything else, with Roger Moore noting how they were “not of any known world.” This did a great deal to help explain their cthulhu-inspired visage, and was something that Spelljammer’s writers really ran with.


But I’m not covering these releases to give a full history of the mind flayer (check here for a semi-correct one if you’re interested), just what they have to do with the planes. Here, Cordell takes that little blip from Moore and builds upon it in a new, only slightly retcon-y way. In a strangely English-written “ancient” tablet called The Sargonne Prophecy (keeping in mind that Illithids don’t even have an alphabet the way we would know it, but rather a sort of fantasy-braille alphabet nearly indecipherable to outsiders…) people find evidence that the illithids came from perhaps somewhere outside the multiverse altogether.

One assumption is that at some ungodly distant time, illithids—or their revolutionary precursors—appeared in the continuum from elsewhere. The fearsome images supplied by the Sargonne text lead one to believe that the point of origin for the illithids’ ancestors was a terrible realm far from our own, from which even the merest contact negatively affected our own continuum. 

“Far from our own,” i.e. The Far Realm. 

While it’s not actually from The Illithiad, Tony DiTerlizzi’s version of a mind flayer from the second edition Monster Manual is the version of them that remains in my head. Damn is it good.

More interesting to me than even this is the explanation of how they have such a humanoid appearance despite their extrauniversal origin. After all, everything else from the Far Realm is far more of a weirdo mess than they are. Here, Cordell supplies an entirely new theory. From the story of a now-dead mage, we learn of visitors to this “Outside” realm (which is to say outside of the multiverse) becoming altered upon contact with its horrific energies. “The far realm from which I escaped bears no tempering. The last visitors became trapped and were horribly altered….” So it may be that mind flayers were humanoids from our universe who, upon entering The Far Realm, became tentacled monstrosities before returning home. 


Hawkins’ tale of visitors (who possibly possessed humanoid forms before visiting this curious place named Outside) goes a long way to explain why illithids, despite their alien physiology, are yet so suited to take sustenance from humanoid brains and reproduce using humanoid forms.

It is a surprisingly good explanation for mind flayers, and even though it slightly contradicts some material from Spelljammer, this is what would stick as canon. I’m still impressed by how smoothly Cordell fixes the strange mess of stories layered onto these creatures over the preceding three decades. The book notes how this refutes other sources (even quoting them at length), and does a good job of saying that if you prefer those explanations go ahead and use them… but really, Cordell’s version of their history is both the most compelling and the most coherent one yet. 

Jeff Easley’s cover art for Dawn of the Overmind.

The first two parts of the mind flayer adventure trilogy stay on the Prime Material plane, and consist of discovering that the illithids plan on darkening the sun of pretty much every world. Cool. Once this plan is somewhat foiled on their own crystal (don’t ask…), the PCs head out on a mission to get transportation to wherever the hell it is the mind flayers are coming from. This they do through an ancient Spelljammer-style ship, and Dawn of the Overmind picks up with them en route to an extremely strange part of the Prime Material plane called Penumbra. That’s right, this is perhaps the only adventure (at least that I’m aware of) to feature both spelljamming and planar travel, which is to say that it connects these two modes of travel in a way that’s only slightly awkward. All of D&D‘s cosmology up until this point can mesh together if you really work at it, though the result is far from elegant.


Penumbra itself is interesting in a way that will likely appeal to Planescape fans, as the PCs go about an investigation in a world largely blocked from its own sunlight, but the real planar content is what kicks up following a dungeon crawl into the ruins of this old planet.1 With the help of a rogue illithid named Strom, known to the mind flayers as The Adversary, the PCs take a portal to the Ethereal Plane. Now remember the Ether gaps that Cordell introduced in A Guide to the Ethereal Plane? Ok, probably not, but here’s this book’s refresher:

Ether gaps are strange phenomena that exist upon the Ethereal plane. Gaps seem to be tiny rips in the Ethereal Plane, holes where the ethereal mists spiral inward like a whirlpool, compacting to form discs of solid ether (also called protomatter) that surround the actual rip. 

Which… sure, why not. But why do the mind flayers give a damn about this? Well:

The illithids discovered a very special ether gap. leading to an alternate multiverse that never came to pass. In fact, the singular ether gap discovered by the mind flayers makers held a multiverse where the ancient illithid empire never fell!

The mind flayers contrived a method to reverse the polarity of the ether gap. in a sense, they hope to turn the gap ‘inside out’ and thereby substitute the what-if multiverse (where they still ruled) beyond for the real multiverse. This would have shunt the current multiverse into an ether gap itself, transforming all of existence into a small rip in the Ethereal Plane of the new multiverse. The illithids hope to reshape the multiverse in such a way that no one would remember a time when the illithids did not rule. The only memory of the relatively illtithid-free multiverse would have lived behind a new ether gap, a location easily forgotten and dismissed by the illithid lords.

The titular Overmind of the adventure is the device the mind flayers created to do all of this ether gap craziness. It requires a lot of power, an insane amount really, to turn the multiverse inside out like this, but then what do you think the mind flayers were doing with all of the energy harnessed from those suns they were destroying? 


With both of these books, Cordell continues to push the AD&D multiverse beyond the bounds of the traditional great wheel. I appreciate his continued love for The Far Realm, which at this point is creeping closer and closer to becoming a true part of the game’s cosmology, but beyond this is the reminder that the multiverse doesn’t need to be static in anyone’s campaign. Planescape’s Great Wheel is a good baseline for the planes of the multiverse, but it’s by no means the limit of what can be done in a fantasy adventure. 

1. Additionally, remember Maanzecorian, that mind flayer deity who got killed early on in Dead Gods? Penumbra features an ancient temple to him, and players get to kill a last vestige avatar of the god, presumably putting him truly to rest with this action. Good times, and also yet another reminder of how much fun Cordell has in tying all of D&D‘s mythology together. This isn’t a Planescape book, but Cordell doesn’t want to ignore the series’ canonical status for any part of D&D.

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