- Medium Humanoid (Blindheim); Chaotic Neutral; CR 2
Another frog-people! I think I've done enough 'how many frog people do we need' rant in this review series. The Blindheim, at least, has a bit of a gimmick -- their eyes that unleashes conical beams of radiant light. And if the Blindheim chooses to focus these beams of light, it's bright enough to 'sear flesh and bone'. Or, well, cause radiant damage instead of confusing and causing disadvantage. That's more or less it, and the Blindheim ends up being a bit of a rare low-CR monster that uses radiant damage, something that might be a bit of a novelty towards parties made up of races that have sunlight sensitivity.
The Blindheim dwell in the fringes of the Underdark, and are ambushers that blast other Underdark species with bright explosions of light to stagger them. I do like the idea that there are so much species in the Underdark that have the 'sunlight sensitivity' trait that another species like the Blindheim has evolved to specifically abuse that.


Depicted as being barely better than animals in their 1E debut, the Blindheim of 5E are a bit smarter, being noted to be 'opportunistic mercenaries' that can be swayed into service with food, weapons... or tales of things from the surface world. They try and make their service in their croaking dialect of Undercommon, and I assume that they would offer their services not just to fight, but to be a source of light in the Underdark. Not a lot of adventures really care about these more environmental effects, but I do like the Blindheim as a bit of a world-building aspect where they are well-suited to interact with surface-dwellers without blindvision. Just, uh, watch your back since the frog-people may betray you.
Lastly, 5E also gives the Blindheim a fun little potential myth and backstory. Blindheims speak of an ancient era where they used to live on the surface, but their ancestors stole and ate a piece of the sun and fled underground, which granted their power. This has led the descendants to be fearful of the sun and the potential 'revenge' of the sun, and the Blindheim will get offended at attempts to speak logic to them (because how dare they suggest the sun forgot their 'great and infamous theft').
5E does make its version of the Blindheim a bit more monstrous, hunched-over with an engorged throat and a set of sharp fangs inside of its maw -- looking more 'frog-like' instead of just 'humanoid frog'. It's not really enough to set it apart visually, but I do like the idea of these mercantile living torches in the Underdark.
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Crab Folk- Large Giant; Neutral; CR 3
Probably one of the more major reinventions are the Crab Folk, ostensibly an update to the 'Crabmen' of the original 1E Fiend Folio. Having appeared in various manuals and in completely different interpretations over the first three editions, 5th Edition continues the tradition by taking their completely different spin on the 'Crab Folk'. The original 1E design wasn't even particularly crab-like, being chitin-covered humanoids with claws... and beaks for some reason. 2E and 3E went for varying degrees of crabbiness that I really like, with 3E's incarnation being a bit more abstract but still recognizable as a 'crab'. Their lore have been quite simple prior to this, being xenophobic sea-dwellers that are often hunted by other beings like Sahuagin because they are tasty.
The 5E visual redesign is cool, but perhaps a bit 'too' cool. It's kind of what you expect from a muscular crab-man.
In 5E, the Crab Folk have a more specific origin story that I'm not the biggest fan of -- mostly because 'cursed into crustacean' is something we already saw elsewhere in 5E with the Aldani lobster-people. These Crab Folk are created by the curse of a green hag (not a sea hag?) that transformed her ogre minions that failed them one too many into more useful forms. They kept drowning, so she gave them the form of crabs. They kept missing the treasures she wanted, so she gave them crab claws to grasp onto chests and a compulsion to always hoard silver.

Since then, the Crab Folk have scattered all over the realms, being mostly peaceful... but sometimes the remnants of the magic of the hag cause them to lash out in fearsome raids. This 'trigger' is actually the sounds of seagulls, which are a remnant of how the green hag had a seagull familiar to command the ancient Crab Folk. They rampage for six days, gathering all the treasures they have won and placing them on the foot of an effigy of their long-gone hag mistress.
It's an interesting enough backstory, but I kind of feel like it's a bit too specific and there are some holes to poke in that story as well. The idea of a cursed race with a 'pre-programmed' instinct is interesting enough, but beyond the vague mention of the effigy it really isn't explored enough what the Crab Folk themselves think of this. Their abilities are also extremely simple, being very simple grappling attacks with claws, which I thought was quite boring.
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Dire Corby- Medium Humanoid (Dire Corby); Neutral Evil; CR 1/2
I've always thought that the Dire Corby were a lot more threatening than they actually are, due to their flavour text. The Dire Corby is a mere CR 1/2 monster with simple melee attacks and the ability to stun and prevent adventurers from taking actions when they hear the Dire Corby's cacophony.
The Dire Corby is as essentially the locust plague of the Underdark in 5E. 'Heralded by the ominous, deep rumbling of their strange song, great packs of dire corbies range across the Underdark, stripping the tunnels and caverns they traverse of all living things. Even the mightiest creatures of the Underdark hide within fortified lairs or step aside from a dire corby flock.' That sounds so cool, doesn't it? I get the mental image of battalions of Drow and Duergar pausing their war because the gigantic living cloud made up of these raven-men are squawking into the massive cavern they are fighting for. Of Umber Hulks retreating to their caverns, of Myconids cowering under giant mushrooms, of savage Troglodytes and Grimlocks fleeing for their lives. Such a cool mental image.


The Dire Corbies unleash a maddening cacophony that stuns the mind, and even causes spellcasters to be unable to unleash all but the simplest of spells. Their design is... not the most interesting. 4E and 5E do make it more threatening, but essentially it's just a dude with talons and a raven head. I almost wish they made the newer Dire Corby a lot creepier just to differentiate it from a particularly lanky Aarakocra or Kenku.
Dire Corbies move through the complex tunnels of the Underdark in a strange but predictable pattern of movement that is compared to migrating birds. Like locusts, they strip whatever they pass bare of lichen, fungus and vermin. Adventurers and intelligent people of the Underdark actually chart the movement of the Dire Corbies, since that guarantees monsters being chased away of these particular tunnels. And some even crazier adventurers plug up their ears, mimic Dire Corby sounds, just to be accepted as part of the pack. That's such a nice little detail to surviving in the Underdark beyond just labyrinthine tunnels and a couple of Drow and Illithid cities! It's derivative of some real-world animals, sure, but that's such a cool description.
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Eye of Fear and Flame- Medium Undead; Chaotic Evil; CR 9
I've always had a soft spot for the Eye of Fear and Flame, one of the many 'intelligent undead skeleton' variants that have shown up over the years in D&D. I think it's just because of how over-the-top long its name is. The Eye of Fear and Flame's description in 5E is remarkably faithful to its original flavour text, noting that it stalks individuals and commands/tempts them to perform evil deeds. If they refuse, the Eye of Fear and Flame throws back its magical hood (which otherwise renders its head as an opaque void), revealing its skull with two gemstones in its eye sockets.
No prizes for guessing what the eye-gems do... one shoots fire, one causes fear. Who would've thunk!
In addition to its eye powers, Eyes of Fear and Flame have access to a couple of minor spells, like True Seeing, Detect Good and Evil, and Detect Thoughts. It really wants to corrupt people and to do its little game. They are noted to appear during times of uncertainty, such as after a group's disastrous defeat, or during moments of powerful choice. They want to corrupt and shake moral foundations, and can even make semi-reasonable arguments. They don't even care about the evil act succeeding, merely that whoever they corrupt does it or not.
Eyes of Fear and Flame are noted to be created by chaotic gods to torment and destroy the lawfulness of other creatures, but other legends speak of Eyes of Fear and Flame being created by the lawful gods as tests. This, as well as a note that there are unconfirmed rumours of only 20 of these strange undead existing, are all taken from 1E.
It's a cute enough twist for sure. With corruptive deals being so much within the monopoly of devils and fey in Dungeons & Dragons, it's neat that there are some weird undead that go around doing it. The mystery on what creates the Eyes of Fear and Flame is an odd one, but one that gives these strange things a mysterious origin without making its entire bio all about it like the Crab Folk!
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Forlarren- Medium Fey; Chaotic Neutral; CR 3
The Forlarren in the original 1E Fiend Folio were half-fiend, half-fey creatures that were created from... unfortunate circumstances, and vacillate between being driven by their fey empathy and their evil fiendish natures, a little bit like a Jekyll-and-Hyde thing. Their 5E counterpart still has the fiend/fey dichotomy, but revises the origin to be just a simple corruption -- satyrs that are corrupted by infernal power. There's also an addition of not just the good-and-evil split, but also an internal turmoil between the lawful rigidity of devils, and the chaotic impulses of the fey. It's an interesting update, and one that helps to preserve the concept of the monster without broaching more sensitive topics.
The design of the Forlarren isn't the most interesting visually, merely being a more scraggly, more ragged-looking satyr -- which is true in both its 1E and 5E art. I get that satyrs have some of the goat-based physical attributes that are often associated with classical pop culture devils, but it's also not particularly visually memorable here. Their stat block is also nothing to write home about, just being a typical spellcsater -- it's their story that's interesting.

5E describes the Forlarren as constantly in struggle with their bifurcated souls, going from being a friendly guide to trying to destroy everything in their path. The two halves bleed into each other, so during its 'diabolical aspect', the Forlarren's natural fey charm can seep through, and during its 'fey aspect', the Forlarren's hedonism is marred by self-destructiveness. It's actually a trope in Feywild ballads of valiant Forlarren who try so hard to be heroic, and to have their diabolic nature emerge and have them betray their cause and companions at the end of a journey.
It's a tragic, sad existence and there's not much in the flavour text that tells us of ways to help them from their fate... save from transforming them back to satyrs, I suppose. It is something that I wished we had just a bit more -- the idea of these monsters that are unwilling and actually loathe the curse placed upon them is great, and it's far better than the Crab Folk above! I really could see some great stories laid out with this concept.
The Forlarren, by the way, are not to be confused with Queen Forlarren from the Forgotten Realms setting. That is just the title of the archdevil Fierna, who was the fiend responsible for the corruption of the fey and the creation of the Forlarren. It is quite odd, I feel, that the new Forgotten Realms sourcebook has a statblock for Queen Forlarren but did not reprint this one!
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Fog Giant- Huge Giant; Neutral Evil; CR 11
The 5E's team's love of giants and the ordning really did show up a lot in the early material, and we get a giant variant here. To be fair, the Fog Giants have shown up quite a bit in previous editions, and the idea of giants that stealthily move through thick sleets of fog is quite a cool one found in many mythology.
Fog Giants are actually a subspecies of Cloud Giants in its 5E incarnation. Cloud Giant position is dictated by wealth, and those who have all their treasure plundered are turned into outcasts -- Fog Giants, who now wander around as raiders and plunderers desperate to regain their hoard. They are still refined, though, and they aren't satisfied with mere coins and gems -- they want the good stuff. Sculptures, artwork, jewelry. Despite being an outcast, these Fog Giants get power over various fog spells, and are actually classified as being a bit stronger than the base Cloud Giants -- if not the many variants.
Fog Giants, being more solo operators, often rely on threats of intimidation to try and get what they want. They either command groups of bandits (but only from 'civilized' people, like humans, elves and dwarves) and do raids on castles and merchants, with the express intent on forcing a surrender and parley for treasure. Fog Giants favour servants that can mingle upon the rich and refined, and would love nothing better than to have them sneak and gather information on pieces of precious art. The idea that these Fog Giants would eventually transform into bandit lords with information networks so wide that other bandits are ignorant of their leader's true nature is fun.
There is a bit of a plot hole, though, since a Fog Giant that has developed its little criminal empire so far that it's become a full crime syndicate surely would've accumulated more wealth? Wouldn't it then want to return to the 'status' of a Cloud Giant?
Regardless, I think I would've appreciated a lot of the other 'bonus' giant statblocks that we keep getting in Volo's and Bigby's if the variants would have incorporated other, older D&D subtypes the way that Death and Fog Giants do.
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Jermlaine- Tiny Humanoid - Jermlaine; Neutral Evil; CR 1/8
Sometimes classified as a type of 'gremlin' in older editions (and it's surprising that the term 'gremlin' is not more widely used as a monster in D&D post-2E), the Jermlaine are tiny little jerks. Despite what the artworks imply, Jermlaines are not actually classified as fey, and are just... really small humanoids. They are about a foot tall, and lurk alongside the shadows, tunnels and caverns of larger folk. They are so good at this that they are actually invisible to Darkvision (flavoured as being a byproduct of its stone-like skin), and being tiny little fellows that hide in the Underdark, they lay ambushes for stronger, larger beings like Drow or Duergar.
Why do they do this? Well, because they hate all taller people. Being so small means that the Jermlaine often become prey or victim to many other Underdark monsters, so their culture is a massive boiling pot of anger and resentment against any taller creatures that enter their domain.The fact that the Jermlaines are hunted for their prized stone-like skin also probably enters into the equation beyond 'tall folk mean!' Ironically, while their skin confers the Jermlaines themselves that darkvision invisibility, they are actually useless in actual alchemical experiments.
An individual Jermlaine is weak (a CR 1/8!) but they make use of their stealth and their magical resistance to gather their entire tribe. They watch the tall people that enter their territory from their small tunnel bases. When time comes to attack, the Jermlaine rely on an overwhelming rush as they attack and overwhelm larger beings. It is odd, mechanically speaking, that they didn't provide us a 'Swarm of Jermlaines' statblock which you'd think would be the easiest way to represent it, but Mordenkainen's Fiendish Folio was released relatively early in 5th Edition's lifespan.
In an interesting little gimmick, Jermlaines are able to also speak and command rats. The flavour text notes that rats are a bit rarer in the Underdark since they are creatures of the surface world (something that other sources disagree with, but it's up to the DM) and signs of a particularly large rat infestation might be a sigh of a Jermlaine colony. As a little easter egg, Mordenkainen notes in this book that a particularly funny interaction is to cast the 'Enlarge' spell on a Jermlaine -- which would cause the entire colony to ignore you and turn on the new 'size traitor'. That's ridiculous but fun!
This is one that I've gained a bit of an appreciation for, after dismissing it as 'boring small-people' in my initial review. I do really appreciate the writeup detailing their adaptation to the Underdark ecology in a way that's really evocative of older bestiaries that spend time trying to craft how these creatures interact with the world around them -- and as fascinating as backstories are, it's these aspects that really make me associate Jermlaines and Dire Corbies and Blindheims with the Underdark!
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Khargra- Small Elemental; Neutral; CR 1/8
The artwork is cool for the 5E Khargra for sure, depicting a Xorn-like creature that's a massive petal-mouthed creature with multiple eyes and at least three scuttling legs... but I feel it misses the ridiculousness and surrealness of the original 1E (and 2E) artwork of the Khargra -- it originally had wings. Wings that look like fins, and the claws were like, these recessed retractable cylinders on the side of its entirely cylindrical mouth. I get that the 5E Khargra is a bit cooler, but this is a monster that was meant to be as weird as possible, I think. It also looks a bit too much like a Xorn, which doesn't really help. I do like the idea that 'naturally evolving' elementals that take certain specific shapes sometimes default to radial symmetry, which reminds me of how Lovecraft describes his alien races like the Elder Things.
The Khargra is described as a flying (even in 5E!) type of Earth Elemental that has a fondness of devouring metal, and often gets mistakenly summoned into the Material Plane by piggybacking on larger Earth Elementals. These guys are also small, and the 'small' size block tends to imply the rough size of a dog, so they fly around and try to latch onto adventurers. Of course, the Khargra finds refined and crafted metals to be a delicacy. Of course they do! Wouldn't be a dungeon denizen without a desire to consume an adventurer's gear. One small piece of mercy is that Khargra hate gold and find it 'flavourless gruel', and organic matter and gemstones are 'repugnant' and causes indigestion.


And that last bit is important -- Khargra don't want to kill you. You taste bad! It's the metal you carry that the Khargra want. And it's at least smart enough to not risk their lives needlessly, only attacking creatures when driven by hunger. That's cute. I like that these aren't just treated as instantly hostile, but as really weird elemental wildlife.
In addition to being just a fun random encounter in general, the Khargra is described to be used as couriers -- like really weird underground messenger pigeons -- by dwarves and duergar. They make use of the Khargra's ability to fly and phase through rocks, delivering messages on scrolls sprinkled with iron dust, and training the Khargra only to vomit it out at its destination. That's cute! Disgusting, but cute!
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KillmoulisI love this guy! The Killmoulis is a tiny little guy with the snout of an aardvark or something, and it's essentially taking the space of a creature like a Brownie that acts as a 'karma fey'. A Killmoulis would manifest spontaneously in the Feywild when an act of charity is performed, and it will go around seeking for travelers to follow. Depending on how it is treated, the Killmoulis will either do boons and help to fix armour or collect herbs. If it is mistreated, however, the Killmoulis's curse and vengeance will cause expeditions to be more tired and dispirited. In-game, this interacts with the Killmoulis either blessing or cursing the party's long rests... hurt this cute little guy, and your next long rest won't even work.
It's a fun little flavour encounter, really, and I always appreciate Fey who are created to be more social interactions. A Killmoulis enjoys travelers, and they like to listen about stories of travelers from places it doesn't know about, and all travelers have something interesting to offer a Killmoulis. It's also a living creature, so it will also happily take payments in candy, fruit and snacks. Sometimes, it doesn't even make itself known -- it just sneaks in, sucks up a day's worth of fruits and snacks, but blesses the party.
The thing is, not every adventurer might appreciate having their food stolen, especially not without their knowledge. Trying to track or attack the Killmoulis (and some people will do that anyway even without reason) and the Killmoulis will curse the travelers. Their rations taste like ash, camping spots are infested with lice, and rocks end up under their bedrolls. Only a sincere apology and an offering of food can soothe the angry Killmoulis.
Lastly, I would note that it's based from a mythological fae from the Anglo-Scottish culture, where the kilmoulis is an ugly brownie that haunts mills -- and sucks up food with its nose because it has no mouth. In their original 1E writeup, their version of the Killmoulis actually references this myth a bit more strongly, noting that they often appear around places like industry (which includes mills).
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Mite- Small Fey; Lawful Evil; CR 1/4
We've got another Fey, and this one is a bit more 'traditional goblin'-y, being a small brutish cave-man with long arms, pointed ears and a snarling face. The artwork have all been black-and-white, although their original 1E incarnation describes them as having violet or light-gray skin. 2E has Mites be classified as a type of 'Gremlin' alongside the Jermlaine. Mites in 5E are described as being annoying fey creatures that like to cause havoc and do horrible pranks.
All Fey in 5E are themed around some kind of emotion, and the Mite is themed around frustration. They are born out of strong emotions of irritation -- specifically ones that causes people to lash out in violence. These frustrated people in the Feywild will sleepwalk into the nearest plant, dig a hole, scream into the hole... and refill it. That person will be relieved of all of his or her anger, but at the next new moon, that hole will birth a horde of Mites. That is fun, and really feels like a very 'fae'-like origin that incorporates a mundane thing that some kids are taught to do to control or sublimate their anger.

Mites mostly live underground in warrens and dungeons, creating hidden burrows similar to Jermlaines that wrap around existing passages and chambers. They set traps to vex travelers, and they just generally sneak in and out and cause as much annoyance as possible. They will jam locks with debris, set up tripwires, and steal away tiny treasures. They don't aim to kill, but to annoy and frustrate as much as possible.
They also have an aura to cause creatures to be more easily irritable and more frustrated -- something that is not demonstrated particularly well by the statblock (which just goes for dexterity disadvantage) but is definitely a fun little roleplaying exercise. That does differentiate them from fellow 'tiny creatures living in the cracks of walls and dungeons', the Jermlaine.
'Mite' is such a fun word to use for the tiny little bastards. It's just a bit of a shame that there's a fair amount of overlap with the Jermlaine. I actually do wish they brought back the old 'Gremlin' monster group for these tiny little jerks to be classified under!
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Needle Spawn- Medium Plant; Chaotic Evil; CR 1/2 (Needle Spawn)
- Large Plant; Chaotic Evil; CR 3 (Needle Lord)
This monster is based on the 'Needleman' in the original 1E Fiend Folio, which is a creature that looks like a zombie but is actually a plant-man that shoots needles. 3.5E would have the Needlefolk show up in 3.5E, still a plant-monster but given a rather cool redesign that resembles a mantis-man made up of cactus parts. 5E's Needle Spawn redesign goes for more 'cool' than 'weird', looking more like Swamp Thing/Man-Thing made up of spiny plant matter. I really wished they had kept a bit more of the 3.5E design since it looked so unique.
5E's Needle Spawn is noted to be creations of the more powerful Needle Lords. Needle Lords are living plants from the Feywild, created out of plants affected by the thirst of violence that suffuses the land. Needle Lords creates seed-pods that embed themselves into corpses, and then grows around it with ropey vines covered with needles. These are the Needle Spawn, which fit with the 'looks like a zombie but is not' gimmick from 1E while also giving it a proper explanation.
The Needle Lord is noted to be driven by a desire to conquer like a general, and views the creation of Needle Spawn to be a creation of vassals. It is implacable, wants to conquer the forests it finds itself in, and often times conflicts against the Needle Lords leads to a 'fight for the forest's soul'. It's not super-fresh, but it's a bit more depth than the original writeup of it hating elves and masquerading as zombies with no real reason.
I do still find the design and monster concept as overlapping a lot with Blights and even other plant monsters like Shambling Mounds, as shooting needles doesn't exactly set you apart from other plant monsters. The motivations are cute enough, and I feel like it's a nice way to give the Needlefolk some much-needed reinvention and depth without mocking the original idea of the concept.
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Norker- Small Humanoid (Goblinoid); Chaotic Evil; CR 1/2 (regular), 3 (War Leader)
The Norkers were described in 1E's Fiend Folio as being essentially just distant relatives of Hobgoblins, but with extra tusks. While the Norkers have appeared in minor supplements in 2E and 3E (mostly described as just being brutish hobgoblin variants), 4th Edition had the Norkers appear in a major book, the Monster Manual III, and characterized them as goblins that have been mutated after being exposed to energies of Elemental Earth. It's a simple but nice little twist beyond just the tusks.
5E Norkers are described as cruel, vicious and lazy even for goblinoids. They share their 4th Edition affiliation with being found deep within the earth. Tying to the 'Maglubiyet conquers the other goblinoid gods' plotline from Volo's Guide to Monsters, the Norkers' unnamed god seemed to be one of Maglubiyet's first conquests -- something that the Hobgoblins are loath to admit. They have thus placed the Norkers at the absolute bottom of the goblinoid hierarchy, giving them the absolute menial of labour, even below regular Goblins, out of spite. It's an interesting bit where the Hobgoblins detest the Norkers, but are not allowed by their god to hunt them down.
The Norkers themselves are fierce and tough enough to fight back against their bullies, however, and are noted to be quite likely to betray and fight back against the more traditional goblinoids. They worship Maglubiyet in their own way, believing that life revolves around the survival of the fittest, and that only those who can endure will be shepherded away to paradise.
It is a bit of a more interesting twist than their original concept, but it really depends on how much you care about the 'hobgoblin conquering host' narrative for all the goblinoid races. I feel like without the slight bits of intrigue from the Norker interaction with the wider Hobgoblin society they end up not having much. It's neat to have more goblinoids, but I really wish that there was a bit more of a twist.
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Screaming Devilkin- Small Fey; Lawful Evil; CR 1
This guy is a weirdo! 'Screaming Devilkin' implies, you know, a devil. Or the kin of a devil. And its appearance is a pretty basic devilish archetype. Bat wings, beastly face, horns, tusks, claws, and a pointy tail. It's just missing a pitchfork and facial hair to be a classic cartoon imp or devil.
The huge plot twist? The Screaming Devilkin are fey. This subversion is true to its original design as well -- even if 'fey' isn't quite codified, the whole point was that this isn't a devil or demon or anything from the Lower Planes.
They are spawned by moments of panic within the Feywild, which ends up creating the image of a devil due to the 'primal fear' inspired by fiendish creatures. Born out of these moments of intense panic, Screaming Devilkins spread fear and confusion, gathering in small flocks to swoop down upon travelers and unleash loud screams that overwhelm a creature's senses. Their screams cause a 'combination of panic, confusion and sensory overload'. They don't actually attack to kill, however, because they want to cause more insidious fear. They'll steal resources, bloody their victims, taunt them... and wait for nature to finish them off.
The flavour text also describes that Screaming Devilkins can appreciate cruelty done by greater villains, and are happy to be a 'horrid mascot' that caper around their new masters, like a twisted Disney villain minion.
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Xill- Medium Monstrosity; Lawful Evil; CR 3
I love these guys! They showed up in the first, basic Monster Manual for 3.5E. They were originally four-armed humanoids with the most vague bug theme in the original 1E-2E, and 3E made them like, bug-devil-men, looking more 'man' than 'bug' compared to the Thri-kreen. 5E turned the Xill into far more monstrous beings, being hunched over with fearsome claws, a secondary small 'Alien Queen' arms, and in fact that whole monstrous alien head really does look like something you'd see on a Xenomorph or a Tyrannid, doesn't it? Cool artwork, even if I do miss the slight goofy charm of the original 3.5E Xill that I was introduced to.
The Xill are more than just bug-people, though. The Xill are dimension-hopping bug-people. They are native to the Ethereal Plane in the original 1E, and coming from a particularly twisted demiplane in 5E. In 5E, Xill are created from a demiplane called Keraptis twisted by evil dreams, created to serve an ancient, long-gone master -- created for ancient tasks.
Xill emerge from the Ethereal Plane to attack prey. While they are fearsome and have a paralytic poison on their claws, they want to abduct their prey, grabbing their prey to abduct back to the demiplane. 5E remains ambiguous what the Xill do with the creatures they have stolen away, but 1E's Fiend Folio makes it clear that the Xill implant their young parasitically and use humanoids for such purposes. I guess it does overlap quite a bit with Assassin Bugs and a bunch of other parasites, and leaving the mystery more open-ended does make it a bit more interesting. A suggestion from the 5E flavour text (which also claims that it is a huge 'maybe') is that those abducted are brainwashed and turned into the forces of the demiplane.
It's pretty cool regardless, being a planar-hopping bug-monster with a strange, mysterious backstory that may or may not be relevant. I do feel like there is a bit of an overlap and some of these lore entries are more about Keraptis or the Green Hag creator than the actual Xill or Crab Folk, which is a bit of a shame. Still, the Xill is pretty cool -- both in its original form and its redesign. Can't complain!