A year and a half after Volo’s Guide to Monsters made its messy debut into the world, Wizards of the Coast released a follow-up in a similar vein. And yes, I know we’re skipping past the almost equally diverse Xanathar’s Guide to Everything, but that’s because its handful of planar-y bits of content had almost no lore attached—the horizon walker, for instance, is a cool concept, but what exactly that entails is pretty much up to each individual player. Mordenkainen’s Tome isn’t quite as much of a weird cornucopia of content as its predecessor in that it features no middle section about player races, making for a 100% DM-focused source book, but its decisions regarding what monsters to include lore about felt even more random. The book’s general theme is conflicts across the multiverse… except when it’s not. And that exception is pretty huge considering that its lore half is five chapters long and only two of them are particularly planar in nature. We’ll touch on all of this below, but in essence, Mordenkainen’s Tome is a set of fairly random lore dumps stapled together with an impressive monstrous appendix, and your perception of the book is going to rely a lot on whether that idea is enticing to you or not.

Personally, I was quite excited when I first heard about Mordenkainen’s Tome. Marginally revamped lore plus quite a few creature oddities from the game’s past is catnip for a player like me, and beyond that it was well past time for something like this; even though the book came out nearly four years after Fifth Edition’s release, little of its world had really been set down. How much from previous editions carried over had been wishy-washy to the extreme thus far, to the point that it often felt like Wizards of the Coast was afraid of saying anything definitive (this, weirdly, has hardly changed even now). Mordenkainen’s Tome doesn’t do away with that overall tone of hesitance, but it does give a much fuller idea of what this edition’s mythology looks like. The general trend of using old names and terms to mean new things that ran rampant throughout Fourth Edition isn’t quite as pronounced, but at the same time very little lore was left truly unchanged. The multiverse looks the same as it was in Third Edition and even Second Edition from a broad glance, but diving into Mordenkainen’s Tome quickly reveals that this is still a new take that’s set apart from any prior editions, for better and mostly for worse.

Chapter 1 focuses on the Blood War, though it’s not the same one that we saw take center stage in Second Edition AD&D (though thankfully it’s also not the boring detente of Fourth Edition either). During the Planescape era, this conflict subsumed almost the entirety of the lower planes. This culminated in the top layer of Hades, the plane halfway between Hell and the Abyss, becoming a permanent battlefield/wasteland. If anything, the Blood War was more important to the planes between fully lawful and chaotic evil, as this was where so much of the fighting actually played out. But in order to clear the way for the Zariel-centered plotline of the upcoming adventure Baldur’s Gate: Descent into Avernus, the Blood War was greatly altered in Fifth Edition. Now, Avernus is the center of fighting, the logic of which is… not great, but is still given at length:

The devils view fighting demons on Avernus as a net benefit for their cause. Although most devils slain there are destroyed forever, ready access to supplies and support from the Nine Hells tilts the tide heavily against invading demons. Also, the prospect of a permanent death compels the devils fighting on Avernus to maintain the utmost readiness and coordination. Wounded devils retreat, knowing that fresh reinforcements can continue the fight. Hordes of lemures, devils that are permanently destroyed only if subjected to holy energies, are used to blunt demonic incursions. The terrain of Avernus is thoroughly mapped and festooned with ambush points, strongholds, and other defensive measures.

In all, this change makes the Blood War far more provincial and as such a less relevant part of the multiverse. It’s cordoned off safely in Hell in a way that wasn’t the case in earlier editions, and as a result can easily be forgotten or ignored in a way it couldn’t before.

The actual Blood War isn’t detailed much more in this book than elsewhere in the edition, and I suggest largely ignoring its material if you’re running a Planescape campaign instead of something centered around the Prime like Descent into Avernus. Nevertheless, this is the longest section of the book’s lore and there’s a lot to dig into, particularly if you’re interested in devils. Asmodeus receives yet another explanation for his actions, this time involving a court case with Primus as arbitrator. It all seems fine, nothing particularly special or engrossing, though at least the entire Hell section isn’t as Asmodeus-centered as Fourth Edition was. He’s still nigh-omnipotent, but somehow less so than half a decade earlier.

More importantly, the new lord of the first, Zariel, receives a full profile and description. Now, Zariel isn’t new to this edition, having been mentioned as early as A Guide to Hell in 1999 (if there are any earlier references I’d love to see them, but that’s the first I could find). Here, Zariel joined Baalzebul’s faction during The Reckoning, presumably having been created by Pramas in order to balance the two sides of the conflict. The main effect of this, really, was to characterize Bel, who prior to this book had been a pretty bland pit fiend general. In Pramas’ hands, he became a loathsome monster who siphoned Zariel’s power and life force and with it took over Avernus.

Bel served Zariel faithfully for many centuries, concentrating his efforts on the Blood War as was proper. In time, Zariel came to trust her underling, and this was her undoing. In the most dramatic coup in the history of Hell, Bel turned Zariel’s court against her and then overthrew the forlorn lord. By a means that has yet to be determined (but perhaps learned during his time among the tanar’ri), Bel was able to imprison Zariel and render her powerless. He then declared himself Lord of Avemus and prepared to repel the assaults that he was sure would follow. 

…

He has been slowly sucking the power out of the imprisoned Zariel, and this has helped him consolidate his power on Avernus

It was a good enough storyline to get mentioned in Bel’s description in the Third Edition Manual of the Planes, which added a bit more detail about her recent state of misery: “It is whispered by his subordinates that Bel still keeps Zariel prisoner somewhere deep in the Bronze Citadel so that he can siphon her hellish power into himself, increasing his own abilities while slowly reducing her to just another soul shell.” This is repeated in the Book of Vile Darkness, as well as the information that “There are no worshipers of Bel. A few scattered cults of Zariel once existed, but they did not transfer their devotion to her usurper.” Finally, in Fiendish Codex II: Tyrants of the Nine Hells, we learned that, “Of all his allies and minions, Zariel herself offers him the greatest aid. Imprisoned in the bowels of the Bronze Citadel, Zariel languishes under the cruel knives of abishai torturers that carve off bits of her flesh to feed to their master.” That was the last we heard about her, alongside a little tidbit saying that, “Legend has it that the fireballs that detonate across Avernus in a seemingly random pattern are generated by Zariel, a trapped former archduke from whom Bel parasitically draws his power. This tale might be true, since the fireballs aren’t really random. Close examination of the phenomenon reveals that they spitefully seek out victims, apparently drawn by motion.”

Weirdly, none of this siphoning or revolting in Zariel’s history makes an appearance in Mordenkainen’s Tome. Since so little was known about her, making her into a fallen angel was compelling, though it’s a bit odd that Wizards did so with absolutely no reference to her past in the game—if you’re going to make an entirely new entity with no real link to the past, then why not go all the way and pick a new name as well? In any case, it’s immediately clear that her story is one that Fifth Edition wants to continue with in the future, making her pages mostly a teaser.

The rest of the archdevils went through fewer changes, though there are a few worth noting. Dispater is somehow even more paranoid since Zariel’s recent rise to power, the edition does its utmost to remove the incest from Fierna and Belial while still leaving it as an option for those who like it (c’mon, it’s Hell!), and Baalzebul is no longer a disgusting slug. Still, the changes are minor, and while it’s a worthwhile read, very little of this is new to Fifth Edition besides those few details above. In addition to the usual archdevils, ex-lord of the first Tiamat is also mentioned in a sidebar as a weird case no one really understands, which is really all that can be said about this vestigial planar oddity.

Meanwhile, the demon lords are even less altered than the archdevils, at least from their most recent incarnations. They’re still far, far less interesting or developed than the versions Paizo gave us in edition 3.5, to the point that despite them receiving a decent number of pages of coverage I still wouldn’t recommend this book to anyone whose primary interest is the Abyss. Those Paizo profiles remain the gold standard that Wizards, and everything since feels disappointing.

Aside from the somewhat by-the-numbers coverage of demons and devils, there are still two wonderful additions to the game: differentiated cambions and tieflings. I loathed what became of tieflings with Fourth and early Fifth Edition, and while I still don’t love how particularized they are to archdevils and demon lords, at least there are more options and with this a bit of diversity in the multiverse. Why all tieflings are still related to devils is unexplained, but oh well, small steps. Cambion differentiation is both smaller and less important given that they’re not a PC race, but I still appreciate the inclusion.

I have less to say about the section on elves, except perhaps that it makes their god a vindictive demiurge of evil and their lot in life miserable beyond belief. So maybe I have a lot to say, though for the most part it all boils down to: “what the fuck?” 

Elves used to be largely like other mortal races in their afterlives. I went back to some older sources after being stunned by the cruelty in Mordenkainen’s Tome and confirmed that, while the overall story of Corellon Larethian has changed a bit with each retelling, elves still essentially worked like other species in the afterlife. Well, no longer. In revenge for their ancestors joining Lolth:

…no elf would ever fully return to Corellon’s embrace to enjoy life eternal in Arvandor. Instead, when an elven soul returns to Arvandor, it is adopted by the other gods of the Seldarine and given respite from the world for a time, during which it is left alone to contemplate its creator’s disappointment. Then the soul emerges from Arvandor, to be reborn.

Elves are caught in an eternal cycle of rebirth in which they can never find rest or true happiness, instead they will always be shown the happiness they could have had and then are shunted back to mortality. There, they don’t sleep (this weirdness isn’t new to the edition), instead they meditate on their racial memories and feel endlessly disappointed. Corellon Larethian (weirdly missing his last name in Fifth Edition?) never forgives and never forgets, and there’s no such thing as a new elf soul, rather they are all simply old souls going through this miserable cycle again and again and again.

What about half-elves, you ask? “Well, ummm… hmm, good question,” answers Mordenkainen’s Tome. As such, we receive a sidebar titled “Half-Elf, Half Soul?” that completely falls on its face in trying to answer this basic question.

From the elven perspective, the birth of a half-elf represents a disruption of the natural order of reincarnation. Elves in different communities and across different worlds have numerous ideas about the nature of the disruption, because the gods have never given an answer that seems applicable to all. The soul of a half-elf might be an elf soul whose connection to the Seldarine has been weakened, or it might be a true elf soul trapped in the body of a half-elf until death, or the soul that lies beneath one’s elf-like visage might be human.

In short, come up with your own answers, because we don’t have one and aren’t going to provide one for you. 

Also included in the elf section is a fuller explanation of Fifth Edition’s eladrin, who are derived from Fourth Edition’s rather than the celestials of Second and Third Editions. However, they’re also not exactly the same as the Fourth Edition eladrin, which leads to a hilarious disambiguation page on the Forgotten Realms wiki that looks like this:

What a dumb mess. Anyhow, the eladrin from this edition are now largely the “Fey eladrin” mentioned above, though also some high elf common eladrin too, I think? Ugh, who cares. The fey eladrin are essentially elves who change appearance based upon their mood, all of which are themed after the seasons. Weirdly, despite having the same elf souls as their distant kin, they’re allowed outside of the race’s gnostic misery cycle in that “Eladrin don’t long to end their cycle of rebirth and rejoin Corellon, but rather to meld with the Feywild when they are reincarnated. They believe that an eladrin who excels in life throughout a series of incarnations can eventually come back as a member of the Seelie or Unseelie court or, in extreme cases, even as an archfey.” Though wait a second, that just says that they wish to do this, does that mean it’s real or just that they have some weirdo desires? Goddammit Fifth Edition, say something definitive already!

So the entire good-elf side of the pantheon is messy, confused, and overall a crappy lot to be born into. Which is not to say that drow elves have it much better—or, for that matter, much clearer. The entire drow pantheon returns to the game, a welcome change in particular for Planescape fans who missed Kiaransalee, though this also brings with it the return of some truly obscure beings such as Ghaunadaur (a weird reddish-purple giant slug deity mostly worshipped by ropers), Keptolo (a god so minor the only reference to him I could find before now was an old Dragon issue), Malyk (a former drow lich who also may or may not be Talos?), and Selvetarm (whose history is so lengthy and confusing I gave up midway through the Forgotten Realms wiki’s entry on him with a shrug). I totally approve the choice of bringing these dregs out from the depths of the game’s history, though I don’t feel like they add too much for a vast majority of players, especially individuals like Malyk.

The real issue, though, comes from the return of the Raven Queen. As is typical with anything even touching upon Fourth Edition, she is not the same individual as before, she just uses the same name and also has a bunch of other similarities… but again, definitely isn’t the same person. This makes sense given that her role in the game’s cosmology is by necessity wildly different, but maybe a better decision would’ve been to just not keep her in the lore at all? Likewise, her backstory with the shadar-kai is altered, and it’s all pretty unmemorable. In short, “It was she who, when Corellon and Lolth were locked in conflict, tried to use the souls and magic of her people to elevate herself to godly status, thus salvaging the fractured pantheon of the elves.” But she failed, went crazy, and along the way created the shadar-kai. If memory serves, this is the fourth origin for that race that we’ve seen, and with each one they’ve become sketchier and less distinct. Accordingly, this also makes them less interesting. The Raven Queen’s realm in the Shadowfell is now called the Fortress of Memories and it’s also pretty wishy-washy, to the point that it feels like something that could’ve been in Fourth Edition for all its dullness: 

Since achieving divinity, the Raven Queen has filled her realm with shadows and memories, obsessively collecting such essences from remnants of dead gods and mortals that were strewn throughout the Shadowfell. From these metaphysical fragments she formed her new home, a twisted castle that the shadar-kai call the Fortress of Memories. The fortress is a mournful place, filled with incessant echoes of the past.

My general sense is that D&D‘s designers felt that they couldn’t abandon this entity entirely given how big a role she played in the storyline of Fourth Edition D&D. However, they did little to make her fit into the game’s new/old cosmology and she’s essentially just there so that DMs who for some reason like her (or the increasingly watered down shadar-kai) still feel free to use them in their games. Which is fine, I suppose, though I’m also pretty glad that this book features the last mentions of her that I can remember reading.

Yes, I’m nearly 3,000 words into this article and am still only now hitting chapter three. Fortunately, at this point the planar material slows down for a little bit. Dwarven gods are back in full force, but aside from them there’s not really anything planar about this chapter. They’re also given much less material than their elven counterparts, and most confusingly of all derro appear in the Mordenkainen’s Tome bestiary but receive not so much as a mention in the section focused on dwarves. Hard to fathom what anyone was thinking here, and as a result we also excise the derro gods from the game largely by default… though they’re also mentioned in the derro entry, just not as deities (huh?). In all, this seems like one of those cases where different people working on the book weren’t necessarily communicating and the result is a hodgepodge in an already hodgery podgery work.

While the gith may be the most planar group covered in Mordenkainen’s Tome outside of the Blood War participants, for once very little was altered from earlier editions. In a way, I actually find that odd, as The Lich-Queen’s Beloved was a seminal adventure that seemed like it really should’ve been incorporated into D&D‘s canon, but alas, that’s not the case. Vlaakith, who may or may not still be 157th of her name, is still running the joint, and while some of the specifics of how she does so have been slightly altered, they’re all pretty minor and largely unnoticeable. Even Tu’narath resembles its previous conceptions pretty well—it’s unsurprisingly a bit simplified, but not in any way that really contradicts the older depictions.

Githzerai tend to be less detailed than their kin (likely because they’re not just straight-up evil villains and so they’re used far more sparingly by DMs), but the material here is consistent with their previous depictions as well. Detailing Menyar-Ag (no longer Zaerith Menyar-Ag-Gith, but that original name is dumb enough that even I don’t really mind the change) is done well, and we retain anarchs and zerths from Planescape. I still feel like Shra’kt’lor’s sketchy depiction could use a massive fleshing out, but that’s not a big deal. The only relevant new material that I noticed was a surprising section about the githzerai’s use of adamantine citadels, a cool addition to the game (or at least one that that I certainly don’t recall from before) that helps even the playing field between them and their dragon-riding cousins. I’m far less fond of the idea of githzerai proselytizing, as this doesn’t seem at all in keeping with the reclusive race—I suspect this was included mostly as an excuse for them to become more prominent (i.e. annoying) in campaigns, but suggest ignoring it entirely as it’s a poor fit everything else we know about them.

Our last section before getting to the bestiary covers the ancient conflict between the, ummm… halflings and gnomes? Do I have that right? Yup, it’s a chapter on halflings and gnomes alright—here’s where the book’s concept truly breaks down, and the justification for this section being a part of Mordenkainen’s Tome of Foes is clearly that the designers didn’t know where else to put it. Both races’ profiles feature a swath of deities that at least at first glance seem full and robust, and I can’t be bothered to check these against older books because I just don’t care, both races always had crazily boring pantheons regardless of the edition. I’m glad these small races got some expanded coverage, but beyond that I have nothing else to say about this section.

Now let’s get down to business, i.e. the more rambling, second half of this article focused on Mordenkainen‘s bestiary. A majority of the bestiary’s monsters are planar, making this book a must-have (at least for a couple years) for anyone who wanted to leave the Prime in their campaigns. As usual, I’ll offer a few pithy comments when it seems warranted, along with a full list of planar entries below.

• Astral Dreadnought – The big beefy boy is back. Seems like there’s more than one still a la Fourth Edition, plus all of the dumb Tharizdun business from back then has been retained. Even the weird digesting-its-victims-in-a-“unique demiplane” business has been retained from Fourth, which I’m not a huge fan of, though I suppose that this has some story potential. In general they feel less epic and momentous than the earlier versions, but that may just be my weird projection. Fourth Edition fans should be particularly happy.
• Balhannoth – A surprising return from this monster that originated in Third Edition’s MMIV and which I’d completely forgotten about since then. Part of this would be that the creature originated in the Prime and was only moved into the Shadowfell once that plane, you know, existed. They have some cool lair actions including warping reality, though given the edition’s general lack of lore for monsters they’re still rather forgettable. 
• Berbalang – While they were fleshed out primarily in A Guide to the Astral Plane, berbalangs never made much of an impression, on either me or the game as a whole. What made them unique back then was that they never met in person, instead meeting up in the Silver Void for socialization and even mating. All of this is gone, and now they’re mostly “weird oracles” who live on dead gods in the Astral and, umm…. yeah, that’s pretty much it. It’s hard to say why Wizards wanted to return berbalangs to the game given how much of their identity has been lost.
• Cadaver Collector – Moved to Acheron from the Prime, which given their flavor makes a fair amount of sense. I’d probably put them into Hades and the Blood War proper as well.

• Demon 
  • Alkalith – Very little lore and far inferior art, but I’m still happy to see them return.
  • Armanite – I should probably just repeat what I said for the alkalith for all of these demons.
  • Bulezau – No longer so tied to Baphomet, so less interesting than before. Why?
  • Dybbuk – I was happily surprised to see some loumaras and obyriths return to the game amongst the usual swath of tanar’ri. Not that the book uses any of these words.
  • Maurezhi – I dig the connection with Doresain, as otherwise they’re dull now given that they now lack the ability to steal not just the appearance but also memories and skills of their victims
  • Molydeus – Super happy to see this longtime favorite uber-powered demon return… but without any new artwork? Really? I also find it kinda funny that their summoning is an optional rule; Fifth Edition is pretty sad, isn’t it.
  • Nabassu – The taboo against eating souls is a new thing, and in general their lore makes little sense to me now. However, I always liked the nabassu as demons who spend a lot of time on the Prime so I’m happy to see them stay a part of the game. Just stick to their information from Faces of Evil or at least Fiendish Codex I instead of the mediocre and half-assed lore we have here and you’ll be fine.
  • Rutterkin – Another stalwart classic who’s been in every edition, here we have two versions, one of which isn’t even all that weak. Hell if I know what edition gave them their diseased bites, but it’s hard to particularly care; it’s not an interesting ability, but it’s better than nothing at all, which is often how Fifth Edition likes to roll.
  • Sibriex – I was surprised to see the sibriex make it into Fourth Edition and am just as surprised to see it crop up again here in Fifth. I really loved these monsters in their original incarnation, and their newest version is totally fine and even comes with a neat flesh warping bit of randomness. 
  • Wastrilith – Back after being gone for an edition, wastriliths don’t look nearly as cool as they did before but maintain their identity as water demons. They’re fine.
• Demon Lords – I’m not going to do more than list who was included in the book. Not that their write-ups here are bad, but there are better versions available for all of these individuals in the old “Demonomicon of Iggwilv” Dragon/Dungeon series, and as far as stats are concerned I don’t much care because I consider these beings Powers and, as such, in my own campaigns their stats are irrelevant. It’s nice to see a few relatively obscure names crop up here (and their artwork is for the most part the best in the entire book), but I don’t think these pages will really surprise anyone who’s been reading this series up until now. 
  • Baphomet
  • Demogorgon
  • Fraz-Urb’luu
  • Graz’zt
  • Juiblex
  • Orcus 
  • Yeenoghu
  • Zuggtmoy

• Devils
  • Abishai – Tiamat’s minions have always been a weird part of the devilish hierarchy, but because we used them a lot when I was growing up I’ve always been fond of them and unhappy with just how obscure they grew over the years. What’s more, all five types get included. 
  • Amnizu – Conversely, these are probably the only classic devil type that I forget exists, likely because I never much cared for/used the original Fiend Folio. Their depiction here makes me think of southern plantation owners, which is a perfect fit for devils. It’s a case where the artwork is so good that I will make an excuse to feature them in a game.
  • Hellfire Engine – These were a surprise addition from Mephisto at the end of 3.5, though I would be more shocked to see them here if I didn’t know what was coming in Baldur’s Gate: Descent into Avernus in the near future. Their Mephistophelean origins are gone entirely, though, making them a lot blander, if obviously far easier for DMs to toss around.
  • Merrogon – Another late-3.5 addition, merregons were also previously known as “Legion Devils.” Unfortunately, they lose what made them so unique, which was their shared pool of hit points. As such, they’re pretty much pointless now (just another CR 4 dude to hit in a game chock full of boring CR 4 dudes to hit), to the point that I’m baffled by their inclusion.
  • Narzugon – I believe the paladin-soul business was added in Fourth Edition. No more baleful gaze ability, but whatever, they’re fine and largely unmemorable.
  • Nupperibo – Who doesn’t have a soft spot in their heart for this oft-neglected devil? I can’t completely blame Fourth Edition for skipping over them, but I’m happy they’re back and still as disgusting and fat-phobic as ever (which isn’t something I’m saying is a good thing, it’s just a fact about their identity). Their role isn’t well-explained, but I suppose that’s why we still have old texts to refer to.
  • Orthon – Yet another Third Edition devil, orthons were large and, until I went back to their old Tyrants of the Nine Hells write-up, that’s about all I recalled about them. They’re now trackers, which is at least a new role for a creature who previously was just another bland soldier. I also dig their newly randomized crossbow attacks, which is the type of dynamic feature you rarely see in Fifth Edition.

• Archdevils – While you might guess that we’d have the same pointlessness here that we did with the demon lords, that’s not the case. Instead, each archdevil is a named individual but not in fact one of the lords of the layers. 
  • Bael – Barely seen in the past 30 years, Mammon’s vasal is similar to his original, First Edition conception. All of the individuals Gygax detailed with a full profile but who disappeared from the game felt like they deserved more time in the limelight, and so his profile was a very happy surprise, even if it did little to add to his lore. 
  • Geryon – Interesting to learn that he’s fighting over in Stygia, trying to retake control. I’m hoping we see more from him in the future, too—wonder what he’s been up to during the last couple editions.
  • Hutijin – Mephistopheles’ right-hand man. Unlike the last two archdevils, I never found him terribly interesting, so I hope that we get more about him than this brief blurb and statblock in the future.
  • Moloch – Now we’re talking. This former archdevil is now even rumored to be found in Sigil, which would mean an epic fall from power considering that true archdevils can’t get into the place. I also like bringing Malagard into his backstory. There’s a lot of cool plot threads to pull at here for enterprising DMs.
  • Titivilus – Prior til now, Titilivus had seemed loyal to Dispater, but now his lord’s trust seems to be a flaw. This again allows for some interesting diabolic plotting, especially with the possibility that all of this is in fact a ruse and that Titivilus might be Dispater in disguise, or perhaps Titivilus has removed the archduke and replaced him altogether. Another wonderful addition to the game’s lore.
  • Zariel – The big spoiler to Descent into Avernus is her prominence in this book. Her recent reclamation of the first layer is interesting, but I’m hoping we learn a lot more about this in the future, as what’s included so far is sparse on details.

• Eladrin – This category includes only the “Fey eladrin,” one of four types of being who D&D has used that name for. They’re kinda like the Fourth Edition eladrin, and perhaps are the root of that race of “high elves,” but are for some reason controlled by the seasons and shift between these depending on the period. I don’t really consider them four types of beings as a result, as it’s just one type of eladrin that can switch about. In any case, it’s not the old Planescape eladrin that we all love and miss, but they are planar beings nonetheless. I don’t much care for them, but I’m generally a hater when it comes to new lore overwriting the much richer old material and the concept itself isn’t that bad—were they a new type of creature entirely I’d probably give them a pass.
• Elder Elementals – Weirdly, these aren’t just big ol’ elementals, they’re specific beings who have elemental facets. 
  • Leviathan – An enormous water dude whose relationship to other versions of the leviathans (the Moonshae Isles one, the elder evil one, and even the big whale one) is unclear.
  • Phoenix – Conversely, phoenixes have been in the game almost since the beginning, and their absence in Fourth Edition was kind of weird (at least, that I remember). The appellation elder elemental was just plonked onto it because why not?
  • Elder Tempest – A new creature that hails from… somewhere unclear. It’s kind of like Third Edition’s storm elemental, which hailed from Air, so I suppose that’s likely where they’re from as well.
  • Zaratan – An oddity from earlier editions of the game (they originated with Monstrous Compendium Al-Qadim Appendix) now repurposed as an earth elemental, I kinda like these big ol’ turtles even if their current conception bears only passing resemblance to its earlier form. Mostly, I think I just like turtles.

• Elemental Myrmidons – Back from Fourth Edition and just as boring as they were there. Meh.
• Gith – Both the githzerai and the githyanki would be very insulted by being covered with this blanket term. Basically, a few subtypes are statted out and offered minimal lore. Pirates of Gith are, unsurprisingly, still nowhere to be found.
• Howler – At first I thought this was their first return since Second Edition, but apparently I’m an idiot because they’ve popped up in Third and Fourth, too. Regardless, I dig howlers, even if that weird chubby neck in the artwork doesn’t match at all with DiTerlizzi’s original. They’re now “found on most of the Lower Planes” instead of strictly Pandemonium, which is often what Fifth Edition often does to planar monsters in order to make them more generally useful to DMs at the expense of their uniqueness. 
• Marut – Now here’s an odd one. Maruts had been part of D&D since First Edition but have never had a consistent identity, likely because they were bastardized from a mythology few of the game’s designers were familiar with. Originally, they were more or less a version of the Vedic originals, but when J. Paul LaFountain brought them into the Monstrous Compendium Outer Planes Appendix he deracinated them from their roots and made them a more generalized, golem-like enforcer of the gods. This was essentially the version included in the Planescape Monstrous Compendium Appendix, but that lasted less than a decade before they became one of the inevitables with Third Edition. This time, designers were coming up with another replacement for the modrons and thought that the maruts should be paired with other, similar beings also devoted to enforcing laws. Then there’s another version yet again in Fourth Edition (not even going into the Eberron version, which is essentially an adapted non-planar version of the inevitable incarnation, at least as far as I can recall), and then finally we arrive at the Fifth Edition marut, which is sort of like the Third Edition kolyarut… but also not. Essentially, the game’s designers never quite figured out how to make the inevitables/maruts work as they wanted, they just knew that there was the core of a good idea there. However, without any of the information that fleshes it out, what we see here in Mordenkainen’s Tome is largely confusing. Who, after all, is the Kolyarut, and what is its relationship with Primus? Or for that matter the Guvners? Maruts are now very usable by DMs as an ultimate enforcer of contracts, but otherwise their lore needs a ton of expansion in order to make sense of their place in the multiverse. In all, I prefer the inevitables version, partially because our knowledge about this newest marut incarnation is still so sparse.

• Meazel – Another super old monster returns. Meazels now appear “in places where the Shadowfell washes against the shores of the Material plane.” What the hell that really means is unclear to me, but they are “all that remain of people who fled into the Shadowfell to escape their mortal existence …. Now, they loiter near Shadowfell crossings to waylay travelers who venture too close to their lairs.” Shadowfell stuff still sucks, I’m sorry.
• Nagpa  – Relatedly, I sure wish the Raven Queen had been lost between editions.
• Nightwalker – Moved to the Negative [Energy] Plane, I guess because even they wanted out of the Shadowfell. Which is totally fair.
• Retriever – One of those Planescape monsters that I never actually used, they’re no longer “living constructs” and instead just normal ones. I think? Housing a bebilith spirit may or may not also be new—they’ve actually been in every edition of the game, I just only consider the Planescape version canon because I’m a jerk like that (i.e.this article is already crazy long already and I don’t want to closely track the changes of a monster I’d forgotten even exists). That they’re more drow-focused makes sense, though for once this limits them rather than making them more generally useful. 
• Salamander, Frost – The most interesting thing about their return comes from the first sentence of their description: “Frost salamanders are natives of the Plane of Ice, also called the Frostfell, which rests between the Plane of Air and the Plane of Water.” I know that none of this is particularly new information, as it’s included in the core Fifth Edition books, but I still find the return of paraelemental planes (often with new names for some reason) worth noting. That Azers go there and hunt them is odd but kinda cool. 
• Shadar-kai – This entry just makes me sad. As noted above, in three editions, we’ve had three versions of the Shadar-kai—and if you include Dragon articles, even more than that. As a result, they don’t have much of an identity besides goth-y elves, which is pretty lame. I never liked their retconning before, but making them focused entirely on the Raven Queen means that I’ll never include this version of them in my games. While their Third Edition lore was both limited and contradictory, that’s still the best we have to work from.
• Skulk – Now a Shadowfell group, a change I don’t really mind because I never much cared for skulks in the first place. I believe they were previously just weirdos in the Underdark, but it’s hard to care either way.
• Skull Lord – A skelie dude now living in the Shadowfell, because why the hell not? Remember when the Negative Energy Plane was where undead came from? Yeah, those were the days.
• Sorrowsworn – Shadow creatures who originated with Fourth Edition’s Manual of the Planes, though I have no memory of that whatsoever, likely because that was a crazily unmemorable book. The Forgotten Realms wiki lists them as derived from the Sorrowsworn Demon, but at this point we’re so far removed that it’s academic. Anyhow, have an emotion-derived theme and are “incarnations of the [Shadowfell]’s bleak nature.” If you like the Shadowfell then you’ll probably enjoy them. If, instead, you’re like me, then you will skim past after observing that their artwork is middling. 

• Star Spawn – I almost didn’t include these creatures in this list, as they’re sort of from the Prime. However, they’re also sort of from the Far Plane, and what’s more, they’re one of my favorite additions to Mordenkainen’s Tome and I wanted to give them a mention. Essentially, star spawn are “the heralds, servants, foot soldiers, and lieutenants of the Elder Evils,” i.e. creatures from the Far Plane (…sometimes). You can think of them as a way of taking monsters like the classic Spawn of Kyuss and turning them into more generalized creatures to be used in more diverse types of campaigns, which is a smart idea and easily modular when you want to make things fit better with a particular evil. As such, the end of this write-up includes almost a page on Elder Evil Blessings, which can be given to star spawn or other followers to individualize them to particular cults. The actual blurb at the end about Elder Evils is unsurprisingly wishy washy and unwilling to say anything definitive, offering up the almost infuriatingly vague information that “Some Elder Evils are called gods, primordials, or fiends . . . . Some Elder Evils are alleged to be creatures of the Far Realm.” Fifth Edition’s love for generalizing and refusal to answer basic questions is so pervasive that at times it’s almost impressive.
• Steel Predator – Their original Third Edition incarnation made steel predators seem a bit like the rust dragons/monsters that also occupy Acheron, essentially supplying another metallic enemy for the plane. The coolest thing about them was their Alien-esque artwork. Their new origin story is plenty flavorful, though it doesn’t match at all well with what we generally know of the modrons: “Steel predators are created by a unique modron, using a machine located in the city of Sigil. It wasn’t always headquartered in the City of Doors, however. On its original home, the plane of Mechanus, the ingenious modron was lauded for its invention—until it turned these creations against its superiors. Steel predators wreaked havoc against the modron hierarchy until the rogue modron was trapped and exiled. Now it operates a shop in Sigil where, for a steep price, anyone can commission the manufacture of a steel predator.” As such, they’re constructs rather than outsiders now, plus their artwork kinda sucks. Neither version really thrills me, but if I had to pick one I’d go with the one that doesn’t badly muddle the identity of one of my favorite races.

• Yugoloths – Our favorite fiends return… only to find their role in the multiverse has been much, much decreased. Not that this is terribly relevant in the bestiary, but I resent what was done to them and can’t help but bring it up whenever remotely relevant. Maybe when this book is de-canonized in a few their lot in the game will improve, though I rather doubt it.
  • Canoloth – What is with that horrendous artwork and its unsightly colors? The yugo-hounds are so ugly now it’s hard to get over it, and their doglike nature has been heavily deemphasized.
  • Dhergoloth – Seems like a fine depiction? 
  • Hydroloth – This is actually my favorite artwork we’ve seen for these ‘loths, at least that I can think of (sorry, DiTerlizzi!). Their stealing memory ability is nicely flavorful, too, and more fitting than the abilities they had in earlier editions.
  • Merrenoloth – Conversely, rather hate this artwork, though I do like that their ships count as lairs, plus lair actions for low CR monsters are always a bit interesting. They seem too weak for their role, but that’s not a huge issue.
  • Oinoloth – A complete change in a stupid, stupid way. The oinoloth/oinodaemon was previously the singular lord of all yugoloths. As such, it usually referred to Anthraxus (later called Phraxas because D&D is stupid), though he was briefly ousted by Mydianchlarus. But in Fifth Edition, we’re instead talking about a relatively weak CR 12 monster with really only one relevant ability, the Bringer of Plagues blight creation. Your basic ultroloth is stronger than one of these fellows, which makes no sense. In essence, this is a totally new type of yugoloth with minimal lore, and their creation continues the edition’s tradition of fucking with the species for no reason and with this making them weak and dumb. What a shitty note to end the book on.
  • Yagnoloth – Solid art. Decent abilities. No notes.

If you do want to add planar creatures and lore to Fifth Edition, Mordenkainen’s Tome of Foes is an invaluable book… at least, it was when it was first released. That the edition’s lore is itself a mess isn’t the book’s fault, and so many of the changes that I found myself frustrated with are natural evolutions of what was already set down. The tendency for this edition to minimize lore and generalize whenever possible is still there, but it’s tamped down at times and as a result there is at least a bit of expansion/explanation to the D&D universe, even if it’s minimal. That being said, the entire book has also since been excised from even Fifth Edition’s canon, let alone 5.5’s, so how much of what’s in here has carried forward is questionable. I like the book for what it is, and it’s the first Fifth Edition book to stay on my shelf, but it frustrated me more than a few times during my readthrough and I can’t say that it truly inspired me with ideas for new adventures.