What Do I Know About Reviews? The Book of Fiends (5e OGL)

New CoverLast year Green Ronin put up the 5e adaptation of The Book of Fiends on Game On Tabletop. I had backed it at the time. Immediately after the crowdfunding campaign, a beta version of the book was available, but now the full version is here.

The original Book of Fiends was released under the 3.5 d20 license for use with Dungeons & Dragons 3.5 edition. It collected the 3rd edition resources Legions of Hell and Armies of the Abyss, and incorporated material that was originally going to be published as a third book, the Hordes of Gehenna. Hordes of Gehenna was primarily designed by Robert Schwalb, a name you may have heard of in modern RPG circles, both for working on 5th edition D&D, as well as his own RPG, Shadow of the Demon Lord. Schwalb is also the primary designer on this version of the book.

Book Bindings

This review is based on the PDF version of The Book of Fiends, which is 256 pages. This includes a full page OGL statement, a two-page index, a full-page bibliography, a credits page, and a table of contents.

While the initial beta version of the book had formatting that looked very similar to previous 5e offerings from Green Ronin, the final book has much more artwork, as well as its own distinct formatting. The major headers have “torn away” chapter headers with big, bold white letters on a red field. There are chain-like borders, and red “slashes” of letters for sub headers. The stat blocks for various creatures look like pages made of flesh.

The artwork is stunning, but a lot of it does run towards the disturbing, which is a good time to transition to . . .

Content Warning

Right up front, we get a nice content warning, mentioning that nothing in the book should be introduced into a campaign if any players at the table are uncomfortable with the content, and I greatly appreciate that. Now, having said that, I think it’s still worth looking at some of the potential issues that come up in this product.

  • Right up front, there is a lot of discussion of bodily functions and byproducts. This comes up more often in the sections on the Abyss and Gehenna, but these topics come up often.
  • There are many instances where children are mentioned, in context of fiends putting them in danger, attempting to corrupt them, or ending their lives. In some instances, some of these fiends are described as attempting to possess or control children, which could cause direct conflict with children.
  • Gehenna, specifically, is largely its own creation, because Yugoloths and the concept of Gehenna in D&D are very specific to D&D. Since the theme of Gehenna in this book are focused around the Seven Deadly Sins, that means a lot of what is “good” and “evil” is partially defined by a medieval version of Christianity. This isn’t overtly stated, but still bleeds over into the narrative just by the association with the concept.
  • Many fiends pull on some BDSM concepts. While it’s never overtly stated, since the only representation of BDSM imagery is being associated with fiends, it’s easy to lean on kink-shaming tropes.
  • When sex comes up, while there aren’t granular details, there are lots of places where non-consensual sex is heavily implied. In addition to the implied actions of some creature’s portfolios, there are some issues with consent that may not even seem to be the case on their surface, such as fiends that can do psychic damage due to triggering pleasure centers.

The content warning is great, and says exactly what it needs to say, but I would have really liked a deeper discussion on how GMs can include some of these themes and content without falling into harmful tropes. I think it’s important not only to have players with the ability to veto content that makes them feel unsafe, but I also think GMs need permission and context to know when it’s not worth doing to work to try and use material.

Old CoverThe Changing Face of Evil

For anyone that was familiar with the 3.5 version of The Book of Fiends, I wanted to touch base on what got translated, what didn’t get translated, and what is new. The original Book of Fiends was about 224 pages, versus the new Book of Fiends’ page count of 256 pages.

Several creatures get renamed, but assuming I didn’t miss any equivalent creatures, about 10 of the creatures from the 3.5 volume didn’t get an update in this edition, and about 48 new creatures appear in this volume. Each of the rings of Gehenna gets a new creature in the form of the souls that are trapped in that ring, based on their primary sin. In addition, several of the ranks of Daemons got more representatives to flesh out the number of mercenaries, whisperers, and watchers each circle had previously. There are a few other new creatures spread out over the three planes covered in the book.

While the 3.5 Book of Fiends was organized by plane, this book has a general section on each plane, then organizes entries by broad creature types, then ends with player and GM facing rules for a campaign. That means that even if a creature is usually found in Hell, for example, if it’s not a devil, it’s going to be in the section with the general fiends.

The original Book of Fiends introduced prestige classes for Balan’s Jackals, The Mountebank, and the Plaguelord, and introduced the core class of the Unholy Warrior. Since 5e is structured a bit differently, and prestige classes aren’t a thing, we instead get the Path of the Infernal Hunt for Barbarians, The Deceiver and The Plaguelord as Otherworldly Patrons for Warlocks, and the Oath of Eternal Darkness for Paladins.

There were two cities detailed in the standard 3.5 layout for city stats in the back of The Book of Fiends. The city located in Gehenna is not mentioned in the 5e Book of Fiends, and the Abyssal city gets renamed and doesn’t have a formal stat block or formatting in the same manner as the 3.5 presentation.

HaagentiThe Spine of The Book of Fiends

This book is largely a book of new creatures, which presents some of the trickier issues with reviewing monster books that I have mentioned before, for example, not being able to give all the creatures a solid evaluation even after reading the book from front to back. However, while this is primarily a bestiary of the lower planes, it is also a sourcebook of the lower planes, its leaders, and player options that interact with fiendish and lower planar themes.

The book is organized in the following manner:

  • Planes of Perdition
    • The Abyss
    • Gehenna
    • Hell
  • The Fiends
    • Daemons
    • Demons
    • Devils
    • Fallen Angels
    • Qlippoth
    • Unspeakable Evil
  • In Service to Evil
    • Character Options
    • Corruption
    • Backgrounds
    • Feats
    • Spells


Most of the time spent on the Abyss describes The Howling Threshold, the first layer of the Abyss, where damned souls first appear. In addition to discussing the inhabitants and the Harvest Gates (portals to deeper layers of the Abyss), there is a mention of a relatively safe space for planar travelers to dwell. I like having that potential semi-safe adventurer’s base in a place like the Abyss. In addition to this detail, The Book of Fiends adds a few details, such as the more cosmic-horror oriented original inhabitants of the Abyss, the qlippoths, and the history of twisted constructs that helped the demons drive out the soldiers of the upper planes.

Gehenna is the most divergent from what D&D players may be familiar with. Instead of an eternally sloping volcanic mountain-scape, the version of Gehenna that is presented has seven circles, each one encompassing one of the seven deadly sins. This version of Gehenna receives the shadow of all mortals, through which the daemons can both watch and tempt mortals as they commit sins that are related to their circle. While there is still an element of Gehenna mercenaries fighting for both sides in the war between Hell and they Abyss, temptation and corruption of mortals is more of a theme than the manipulative long game that the Yugoloths seem to play in the “standard” D&D cosmology.

Hell is another location that is slightly different, but recognizable when reconciled with the D&D version of the plane. This is probably because the original Legions of Hell was written by Chris Pramas, who also worked on the AD&D version of hell during 2nd edition. There are a few archdevils in charge of layers that don’t line up with the current 5e rulers, but you’ll still recognize part of the hierarchy, such as Mephistopheles being the second in command to Asmodeus.

Exarch of EnvyRulers

The demon princes and lords, archdevils, and exarchs of the Deamons are described in this section. Many of the “named” archfiends that already appear in D&D don’t get much information provided for them, but there are references to entities like Demogorgon, Orcus, Belial, Mephistopheles, and Asmodeus.

The beings that are detailed aren’t given full stat blocks. In the later section, where monster details are provided, there are less powerful lords and dukes, but the “top tier” are presented more in terms of their cosmic goals and their long term plans.

Because Gehenna is largely redefined, we learn that, not unlike the default hierarchy of Hell in D&D, not everyone in the hierarchy is a native fiend from that plane of existence. One of the exarchs of the daemons is actually a slumbering, exiled devil, and another is a dracolich that has become part of the hierarchy of the plane.

In general, even if you are using the standard D&D cosmology and its rulers, many of these rulers can be slotted into the default cosmology. Only the characters at the very highest echelons of power tend to be incompatible between versions of the plane. Gehenna, however, feels like it’s probably better used either with the default D&D version, or substituting this version of the plane, with all of the interlinked themes.

If It Has Stats, We Can Kill It

The next section of the book includes all the creatures that are presented with stat blocks. These are broken up mainly by creature “sub-types.” Many of these creatures are fiends, but they are subdivided and split between the various factions in these planes. The daemons are even more subdivided and organized under which of the circles of sin to which the daemon belongs.

  • Because of the highly thematic nature of daemons and how they are presented, there are also sub-categories of creatures as well. Each circle of Gehenna has specific stat blocks for the souls that are trapped there. Each of the circles has its own thralls, as well as mercenaries (troops that serve as the rank and file, and that are also loaned out to Hell and the Abyss), watchers (daemons that peer through the mortal’s shadow to witness sins, and may have specific conditions under which they take action), whisperers (daemons that whisper through the mortal’s shadow to tempt them), and servitors (the “court” of deamons that serves the exarch).
  • All the demon entries include a summoning variant rule, and in addition to presenting a variety of demons representing different styles of chaos and evil, there is also an underlying theme about a specific council of demons trying to enforce their own conspiracy across the infinite layers, complete with their own enforcers. There is the demonic equivalent of rakshasas, demons infused with entropy, alternate demonic familiars, and horde demons. Horde demons are almost a throwback to the random demon generator in the 1st edition AD&D Dungeon Masters Guide, where there are least, lesser, and full horde demons with varying appearances and base statblocks.
  • Many of the devils presented are specialized beings serving a particular duke or archdevil. In some cases, they are servants of dukes presented in this volume, such as Balan, the master of the Infernal Hunt, and his mount, or the shapechanging agents of Hadriel, a duchess establishing a secret society on the prime material plane. There are assassins that work for Mephistopheles, and sentinels that are native to Avernus. There are also several stat blocks for various lesser dukes that can be used for campaign villains.
  • Fallen Angels are a tricky designation. They are all celestials, but due to some technicality, they are exiled from the upper planes, and have not become fiends. In some cases, this is because they were exiled before Hell even existed. There is a specific fallen angel stat block, as well as some “famous” fallen angels from across time and the cosmos.
  • Qlippoths are strange inhabitants of the Abyss that are currently hiding and plotting against the demons that took over the plane later. They are the original inhabitants, and they have elements both of demons and of cosmic horrors, often with mutable forms and the ability to vary the patterns on their skin to fascinate other creatures.
  • The Unspeakable Evil section is kind of the “grab bag” of monsters. They are all creatures that live on the lower planes of varying types that aren’t part of the species previously listed in the book. This includes singular creatures like the Armageddon Beast, dragons, constructs, fallen titans, not-quite demigods, predatory beasts adapted to the lower planes, and the undead shades of angels. This includes one of my favorites, oubliettes, constructs made to decapitate paragons of good to keep their head alive, witnessing Hell’s atrocities until they finally give in to despair (and keeping them alive to be rescued by adventurers).

Reading this whole section reminds me how much not just the monsters, but the structure of the D&D planes is influenced by Abrahamic religions. I’m curious what it would look like if evil creatures not native to the living world from other cultures were given their own spaces to shape the overall narrative of a plane, instead of being put into a corner of something that looks like a medieval Christian conception of Hell.

If you are looking for a wider range of monsters that your players aren’t likely to recognize, these monsters work for that. But most of them have an attached packet of lore that makes them good to build a narrative around. Some of these monsters foreshadow other infernal powers that might be in play. Others might be the source of various local curses or afflictions. Throwing a construct into an encounter that has a history as an impossibly old war machine adds more gravitas over a well-recognized golem.

TPK DemonDevilish Designs

I just wanted to note a few recurring elements in the design of these monsters. There are several “powerhouse” monsters that have a feature that lets them roll their weapon damage three times on a critical instead of two. There are also several Legendary creatures that give the creature the option to cast a spell, which isn’t limited by level, unlike some of the current design behind spellcasting Legendary creatures in the core, official rules.

Some creatures bestow corruption, which interacts with the rules that come up later in the book. In addition to inflicting corruption, many of these creatures that bestow corruption have mechanics that do more damage to corrupted creatures, or that impose disadvantage on saves versus certain abilities if corruption is in play.

Evil Characters?

There are several character options introduced in this section. This includes two barbarian paths, three cleric domains, a paladin sacred oath, and three warlock otherworldly patrons. The disclaimer at the beginning of the chapter reiterates that you should make sure the entire group is comfortable with characters using these options before introducing them into a campaign, and it notes that most of them will have a hard time being used in a standard heroic campaign.

The first barbarian path is the Path of Hatred, which plays with generating hatred tokens while raging, and assigning them to various foes to do extra damage or to grant advantage. Eventually this also causes opponents to save versus fear, and you may be able to burst out of bonds or generate tokens when you take damage. I kind of like the idea of playing with rules around generating and spending these tokens, and while the idea is that the barbarian has an unhealthy hatred for anything that opposes them, this is one of the options that feels the least disruptive to include in a campaign.

The Path of the Infernal Hunt is a lot less ambiguous about embracing evil, especially if you read the sidebar on the initiation ceremony. This path plays with transforming to gain additional benefits in combat, gaining wildshape, telepathic communication with animals, and the ability to summon hell hounds. Honestly, if it weren’t for the initiation sidebar and the hell hounds, this could be adapted to a pretty standard shapeshifting barbarian archetype.

The cleric domains are Fear, Pain, and Ruin. Because cleric abilities tend to be kind of rigid in their presentation, there isn’t a lot to say here. Pain clerics can incapacitate with their channel divinity, as well as gaining resistance to damage. At 17th level they can create a field of vulnerability. Fear clerics get the heavy armor boost, cause fear (who could have seen that coming), and maybe make opponents even more afraid and drop stuff. They can impose disadvantage when they are attacked, and their capstone domain ability is that they are immune to fear and saves against their fear is at disadvantage. Ruin clerics can create difficult terrain and use their reaction to do psychic damage to opponents that miss them in combat. Their domain capstone is an earthquake effect.

Honestly, fear isn’t that interesting to me, and the only ability I really like out of the Fear domain is imposing disadvantage as a flash “mini-fear” effect. I couldn’t help but think of how a cleric of Ilmater (the lawful good god of suffering from the Forgotten Realms) could use the pain domain, and I think it would work, but the domain spell exquisite pain does feel like a little more than “spread the pain to those that cause pain.” I also think it would be easy to reflavor a Ruin cleric as a non-evil cleric of a god that just knows when and how the world is going to end. Yes, I played a cleric of Jergal. I would give this a whirl.

The Oath of Eternal Darkness does not, unfortunately, give you access to the best video game ever produced. It does, however, give you abilities like causing fear, corrupting your weapon to count as magical, creating an aura of darkness, and seeing through darkness. Your capstone ability transforms you into a shadow creature that gives you a vulnerability to necrotic damage, but makes you resistant to bunches of things, immunity to necrotic and poison damage, the ability to hide in dim light, and the ability to do additional necrotic damage.The Oath includes Despair, Hatred, and Relentlessness as tenants, and between that and the general themes you are playing with, yeah, this one probably stays on the villain side of things in most campaigns.

The warlock patrons are all essentially specialized versions of The Fiend otherworldly patron, tailored to specific types of fiends. The deceiver allows you to gain a per rest reroll because of your plotting and schemes, make saves with advantage, transfer damage to other creatures nearby, cause creatures that hear you to gain corruption, and you get a super charm effect. The plaguelord warlock can poison in a radius around them, use a reaction to attack damaged creatures, grow insect wings, and eventually get the ability to do disease damage when you hit with an attack, doing poison damage that also lowers maximum hit points. The demon lord warlock is detected as if they are a demon for effects that do so. It gives you a pool of dice to grant allies to aid your attacks, which cause psychic damage if they miss. Later, it grants temporary hit points, and the ability to make charisma checks with demons at advantage. Eventually you do damage in an area around the spot where you summon a demon.

Since most warlocks already play with the theme of “can I do heroic things with a creepy patron,” I don’t think having an evil patron is a non-starter. However, having an ability that expressly causes corruption would nix that in most campaigns, and while I like the thematic of “I’m giving you a boon that will harm you if you don’t succeed,” I’m not sure that helps build party cohesion, so I can see that one being reserved for very specific campaigns as well. I also wonder why poison is the favored damage for the plaguelord warlock instead of necrotic.

In Service to Evil I’m used to the concept of corruption from Shadow of the Demon Lord, and I actually like tracking corruption more than micromanaging alignment. That said, one of the effects is an alignment change, so it’s not the best way to completely replace alignments in a campaign. If you have played Shadow of the Demon Lord, the corruption track probably does feel at least a little familiar. You go from gaining a flaw, to rolling for a lesser corruption, changing alignment, rolling for a greater corruption, and finally, rolling your death saves at disadvantage because the fiends want to bring you home. Lesser corruptions are only negative, while greater corruptions give you a bonus and a penalty to different activities.

I would much rather the corruption flaws be determined by the player, as a negative version of something that is already true about their character. I also dislike that several of the corruptions are physical debilities. When things are completely alien to human appearance, like having fire in your eyes, growing horns, or gaining spine ridges, that’s fine. I don’t like the idea of weight gain or a disabled leg being signs of evil.

All the feats presented are ability boost + benefit style feats. They all revolve around being the favored of one of the Exarchs of Gehenna, meaning that a character is an exemplar of one of the seven deadly sins when they take these. Unlike most rules in D&D 5e, these all have an alignment prerequisite of evil. Most of these give you an extra ability, such as wrath giving you the ability to use a reaction to attack someone nearby when you take damage.

The spells have a mix of summoning effects that target specific monsters from this book, or damaging effects that have secondary effects, like breaking bones in a manner that also paralyzes the victim. There is also a spell that involuntarily causes sexual pleasure that I would X card right out of just about any game I was in.

Rule In Hell

This book has so many story hooks in it. In some ways, all good monster books provide those, but these are some deep, interconnected plot elements that you could build a campaign around. Even when you don’t want to dive that deep, it gives you lots of great variations on archetypes that are fun to swap in for anything that might feel a bit more mundane, as long as it makes sense to introduce a touch of the lower planes. The sections on the lower planar leaders is just rife with campaign material. I’m very happy that the content warning goes beyond just disclaiming responsibility for bad actors or saying the material isn’t for everyone, but instead discusses consent, safety, and the active use of safety tools in the game.

Hell in a Handbook

I wouldn’t say there is anything in this book that isn’t fit for any campaign, but there is a not insignificant amount of material that isn’t going to work for a lot of campaigns. While its fine for a GM to ask players what is and isn’t okay to introduce, this also means that a GM should take care engaging with the material to begin with. I know reading this cover to cover to do a review had a heavier impact on me than if I were just to read bits and pieces for a campaign. Additionally, if you have an affinity for D&D’s native Gehenna and yugoloths, it could be cumbersome to reconcile this material with the default cosmology.

Qualified Recommendation–A product with lots of positive aspects, but buyers may want to understand the context of the product and what it contains before moving it ahead of other purchases.

This book is obviously well crafted. There are so many details and plot hooks, and such a variety of horrid opposition for campaigns. That said, because it deals with a lot of disturbing topics, some of which may have questionable use for most game tables, someone purchasing this really needs to weigh that factor as well.

If you are willing to wade through the material with care and critical thought, there are so many gems in this book. This topic, examined with this level of detail, was never going to be for everyone, but it’s important to remember in our enthusiasm for good game material that there may be some items that just fall outside of our comfort zone.


I put together this spreadsheet of the monsters included in this book, which can be sorted by type, subtype, and challenge rating, and includes the pages where the stat blocks are located.

The Book of Fiends 5e Monsters by CR


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