The Lion's Dungeon

Phaerimms are another creature from previous editions of the game that have been alluded to in 5e’s lore before (in this case, within the flavor text description of Icewind Dale: Rime of the Frostmaiden’s grotesque tomb tapper constructs), but only given a stat block now, and only in a book that very few are likely to have heard of. These highly intelligent funnel-shaped aberrations with rows and rows of teeth dwelled in the Underdark and posed a particular problem for the ancient Netherese of 5e’s Forgotten Realms setting due to their evil magic draining the vitality from the world, which is why they designed the aforementioned tomb tappers specifically to go out into the Underdark and exterminate them alongside other threats such as the mind flayers. They were nearly successful in this endeavor, but a handful of phaerimm survived and are now motivated primarily by their desire to rebuild their population. Of course, with each phaerimm only being able to produce one egg every century,...

Bebiliths are a monster that I’m honestly surprised haven’t gotten a stat block until now, and in a book that hardly anyone has heard of no less, but they are the powerful spider demons that drow pull from the Abyss to stuff into their mechanical retrievers (or at least used to; the new flavor text for them in Monsters of the Multiverse doesn’t seem to make any mention of them). Aside from this means of summoning their spirit to the Material Plane, bebiliths are stated to not be able to be summoned away from the Abyss, meaning that it won’t be encountered anywhere other than the one place that it can be permanently killed. Bebiliths weren’t actually created by Lolth like one would expect, and are instead theorized to be some of the first demons in existence. They hunt other demons primarily, but will attack anything they come across in the Abyss, and with their CR of 12, they are definitely a high level party encounter only. Bebeliths’ highest ability score is their exceptional Dexte...

Demodands are fiends that were exiled to Carceri for their evil, but view themselves as the wardens of the Prison Plane instead of prisoners held within it, effectively operating under the philosophy that if they can’t escape, nobody can, including planar travelers who are just passing through. Strangely, however, the book itself does provide a notable example of them being outside of Carceri in the Underdark prison of Carcerus, a creation apparently unique to this book which has a portal to Carceri and is infamous as the most secure prison in the Underdark. Feel free to ignore this exception to the rule, as it doesn’t seem to make a lot of sense when you think about it. The demodands live in a caste system split up into three tiers, with farastus serving as the lower class performing menial tasks and cowering in the face of their superiors, kelubars serving as the middle class handling the day-to-day operation of the demodands’ prison system, and shators serving as the ruling class an...

Skeleton warriors are formed by skilled necromancers out of the remains of great warriors that retain their ability to speak and their considerable combat skills even after death. This essentially makes them super-skeletons, with much higher AC, hit points, and ability scores than typical skeletons possess across the board. More than this, however, skeleton warriors have immunity to the charmed and frightened conditions, resistance to cold and necrotic damage, and outright immunity to nonmagical weapon damage, at the cost of now being vulnerable to bludgeoning damage from magical attacks. They also come equipped with Magic Resistance and Magic Weapons in the form of a +3 greatsword that, for balancing purposes, I would recommend only functions as a +3 greatsword when held by the skeleton warrior that wielded it in life. Their highest ability scores are a three-way tie between Strength, Constitution, and Intelligence, curiously enough. They’re not just brutes, but rather cunning brutes,...

Dread doppelgangers are old doppelgangers that have lived for centuries and taken on hundreds of forms, an experience which has left them utterly devoid of empathy and desperate to feel any kind of emotion, as well as giving them a rather horrific appearance compared to younger doppelgangers. They have similar ability scores to doppelgangers, with slightly higher Dexterity, much higher Intelligence, and slightly higher Wisdom, along with a bit more hit points. They retain all of their doppelganger abilities on top of one more Slam attack in their Multiattack, although they curiously lack younger doppelgangers’ immunity to being charmed. They also gain a degree of innate spellcasting abilities powered by their Intelligence which, like several other monsters I’ve covered from this book, do not require any components. This little quirk of their innate spellcasting turns what would otherwise be a somewhat unwieldy set of innate spells (three daily uses of Phantasmal Killer and one daily us...

Achaierai are, as the flavor text describes, “cunning avian quadrupeds” who hail from the plane of Acheron, yet often find themselves in the Underdark. One rather curious fact about them is that they can only breed on the plane of Acheron, leaving them dependent on capturing spellcasters with access to planar travel in order to force them to bring others of their kind to the Material Plane. They band together in flocks of up to half a dozen, led by the biggest and strongest achaierai among them, and are remarkably cruel to their victims and even their fellow achaierai. Because of the size of their flocks, their CR of 5, and their potential goal of capturing high level wizards to open up portals to Acheron, these guys are a high-level encounter only, save for the rare situation where a mid-level party encounters a single achaierai that has been separated from their flock for whatever reason. Their highest ability score is Strength, but all of their ability scores are above average save ...

Wolfweres are, as the name might suggest, wolves that turn into humans rather than humanoids that turn into wolves a la werewolves. Despite this, they are actually listed as humanoids with the “Beast” and “Shapechanger'' tags, which introduces a curious bug in their tactics that I’ll go over later. The scenarios in which these cunning predators can be encountered vary considerably: some your party might encounter operating on their own as a hunter or while infiltrating a humanoid settlement, some your party might encounter in familial bands led by a wolfwere alpha, and some your party might encounter leading a pack of wolves or worgs as their intelligent canine overlord. Each of these different scenarios presents different tactical opportunities for the wolfwere, meaning that each of them will have to be examined. Wolfweres’ highest ability scores are their excellent Strength and their above average Dexterity, while their Constitution is slightly above-average, their Intelligen...