D&D Monsters: Mind Flayers

The mind flayer is a creature original to D&D and, like many of Gygax's early creations has a "does what it says on the tin" style name. To my mind, it's one of the better such names - although almost anything is better than, say, "lurker above". The look of the creature is obviously reminiscent of H.P. Lovecraft's Cthulhu, and Gygax stated that it was inspired by the cover of a book by Brian Lumley that does, indeed, feature a being from the Mythos. But, as it happens, it isn't the Big C himself that's on the cover, but a chthonian, a creature with a similar name, to be sure, but actually rather different. Still, it has tentacles and this, seemingly, was enough.

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1E

The mind flayer goes through relatively little change in physical appearance through the various editions of the game, to the extent that the few changes that are apparent could easily be put down to variations between individuals of the same species. Even the clothing doesn't change much, with the race clearly having a preference for robes and insisting on a skull motif somewhere on their belt. 

In 1E, they appear as hairless beings with four fingers on each hand but otherwise with a torso and limbs that appear essentially humanlike. The head is the key point of difference, being ovoid and lacking any apparent ears or nostrils. The mouth is concealed behind four smooth tentacles - these are said to be black, offsetting the mauve colour of the rest of the creature's skin, but this detail disappears in all later editions. The text states that the eyes are dead white without any apparent pupils, although the accompanying illustrations both show vertical, cat-like pupils and eyes that are large enough for these to be unmissable.

Considering it isn't wearing any armour, the mind flayer is surprisingly hard to injure. A rubbery hide might go some way to providing natural protection, but it seems more likely that high agility is intended, which might also explain its combat prowess as implied by the hit dice - much higher than, say, an ogre. They have a "genius" level of intelligence, putting them on a par with the top 2% of humans, assuming we take the 3D6 distribution of the stat literally. Seemingly possessing a civilised culture of some sort they are "rumoured" to have a city somewhere deep beneath the Earth.

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2E

By 2E, the rumour has seemingly been confirmed, since the existence of one of more mind flayer cities is stated without qualification. It's also here that the name of "illithid" is first used in a core rulebook, along with further information on the race's biology, especially its method of reproduction. We are told that there are two subraces, one with an octopus-like beak and one with a lamprey-like maw, but the former is not mentioned in subsequent Monster Manuals, since its real distinguishing feature is something that doesn't fit with the core rules of later editions. This is also the only edition in which we can see the mind flayer's feet in the rulebook illustration; they turn out to be somewhat elongated and bilobed, perhaps with a pair of wide toes.

The illustration we do get, however, does include the blank white eyes mentioned in 1E. In reality, these would be a really bad idea. White, by definition, reflects light, which is the last thing you want the front surface of an eyeball to do. One possible conclusion is that, living in near-perpetual darkness as they do, mind flayers are blind in the visual spectrum, using their eyes only to 'see' with darkvision... but there's nothing else to support this theory.

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3E

The mind flayer in 3E has a distinctly greenish tint to its skin, and proportionately longer tentacles and smaller eyes than the previous versions, but these points are relatively minor. We're told that their skin is slimy, presumably in the way that of a frog would be, and that they constantly drool saliva... which is rather harder to explain. A waste of water and nutrients, one would think.

The armour class hasn't changed, although much of it now apparently due to the hide of the creature, which must be significantly tougher than leather. Still, it is notably agile, and its intelligence rating is even higher, now being off the top of the regular human scale. It's perhaps clearer than before that mind flayers like to surround themselves with slaves (usually grimlocks, which appear to be loosely based on H.G. Wells' morlocks). Which explains where their clothing comes from, given that the concept of a mind flayer working as a tailor seems a bit hard to swallow.

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5E

The mind flayer is back to its regular mauve colour here, although the eyes do seem to have small pinprick pupils. In which case, since these wouldn't be of much use in low lighting conditions, perhaps the illithid shown is in comparatively bright light making its pupils contract. That would imply that the eyes are normally dead black, rather than dead white, but the text doesn't specify either way, so both options work.

Although it is less agile, and marginally less strong than it was in 3E, the more important attributes for the race remain unchanged. The mind flayer remains above the normal maximum human intelligence, and is resistant to magic (although it was near invulnerable to regular spells in 1E, so that's still a downgrade). Its armour rating doesn't change either but this time this isn't due to extra-thick skin, but the fact that it's literally wearing armour, rather than the unprotected robes of earlier editions.

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Mind flayers are considered to be "aberrations" rather than regular monsters, but what exactly does this mean? The description of the term indicates that it applies to creatures that are particularly alien, either anatomically, or in terms of their mental processes. The mind flayer presumably falls into the latter category, since it isn't really any stranger looking than many other creatures. 

But, where it's physically defined, there's no real way to draw a line that indicates what would be alien enough to count. After all, if a roper isn't strange enough, it's hard to know what would be. We could try and fall back on the distinction in 3E, which indicates that aberrations are less effective in combat than "magical beasts" with the same number of hit dice... but this doesn't help, since hit dice are an entirely arbitrary concept that isn't rooted in anything objective. 

We're left with the idea that an aberration is anything alien enough that spells and abilities designed to target regular monsters (magical beasts or "monstrosities") won't work on them. Which doesn't really explain why they are themselves a category, so that (barring any specific immunities) a spell that works on one aberration also works on all the others, despite them specifically being heterogeneous. It's a perfectly reasonable rules construct, but not one that can be rooted in anything objective about the world itself. 

This isn't to say that sages within the world wouldn't draw the same distinction, since that's pretty much what a lot of pre-Darwinian taxonomy was like in the real world anyway.

As to the mind flayer specifically, there has been a surprising amount published about their biology. Their general body form is clearly humanoid, implying a roughly human-like internal skeleton. The only real differences from a standard tetrapod form are the facial tentacles and the apparent absence of nostrils. The first of those, however, isn't much stranger than a catfish having barbels. As for the nostrils, it appears that the creature breathes through its mouth, rather than them being present but hidden by the tentacles.

Some editions describe the mind flayer as being an amphibian, although it's unclear quite how far we should take this. It may simply be intended to indicate that mind flayers spawn as tadpoles (something that's clear from 2E onwards) before metamorphosing into the adult form, rather than that they have any other features in common with frogs - or with bullywugs. If we take it literally, however, it implies that most of the internal organs at least approximately match those of humans other there would be changes in the fine details, such as the number of chambers in the heart. Just as likely, though, they're alien entities with a humanoid skeleton (with an odd-looking skull) but an otherwise peculiar internal layout.

The signature power of a mind flayer is, of course, its mind blast. The word "psionics" was coined in the 1950s to indicate an imagined science of psychic powers, but was never all that widely used by parapsychologists themselves, although it was popular in the science fiction of the '50s and '60s. Since then, it seems to have declined further, with the exception of its use in RPGs and media inspired by them. That such games first appeared in the '70s and were written by people inspired by the works of the previous two decades is hardly a coincidence.

At any rate, psionic powers, as described in RPGs aren't really any different from magic, even if the terminology used is often different. In the case of the mind blast, we can say that it probably works on the intangible soul, rather than the physical brain and isn't the sort of thing one could measure without using some other form of magic. It's not obvious that most people within the world would consider it as any more than a slightly unusual form of sorcery. Indeed, both 3E and 5E describe it as duplicating spell effects in the core rulebooks, which is where I will leave it.