Codex Adeptus Mechanicus

Book review

settings wargame scifi

I play an Adeptus Mechanicus army in Warhammer 40,000 and the new Adepus Mechanicus Codex recently came out. I've purchased it and read it from cover to cover, and this my review of it. In short, it's good. I'll talk about why in this blog post.

Before talking specifics though, it's worth explaining what a Codex is in Warhammer 40,000.

What is a codex in Warhammer 40k?

In Warhammer, a codex is primarily a rulebook, but it contains only the rules specific to the army you play in the game. Most importantly, a codex contains specifications ("datasheets" in Warhammer terminology) for your individual miniatures so you know how far each soldier or tank or robot in your army can move, how powerful its weapons are, how strong its armor is, and so on. This is information you must have in order to play a game of Warhammer, and it's not information that doesn't typically come in the box of miniatures you buy (unless the box you've purchased is a self-contained game or a starter set with special rules all its own)..

In addition to rules, a codex also has a primer on the lore for your army. That's not really something you need to know in order to play, but if you're a fan of the Warhammer books and setting, then it's fun to read.

Is it worth it?

If you're buying the Adeptus Mechanicus Codex for the rules, then this book is absolutely worth the cover price, although it's not the only way to get the datasheets for your army. Games Workshop also sells datasheets on individual note cards, and I'd have purchased those in addition to the book, but my local game store had just sold out.

If you're buying it for the lore, then this book is probably not worth the cover price. The lore is good, but only 40 pages out of 120 pages are lore. Then again, I don't know offhand where to find more Adeptus Mechanicus lore all in one place, so maybe this book is worth it. Even if you don't use the datasheets for a game, they do at least give numbers to the relative strengths of different soldier types and machinery. But lore doesn't change that much, so I'd probably just look out for a previous edition's codex and buy that.

What's in the Adeptus Mechanicus Codex?

The Adeptus Mechanicus Codex contains lore, photos of painted miniatures, and rules for both Combat Patrol and full-scale armies.

The lore

The first 40 pages of the book is all lore. You get a history of the cult, with some details you might not have known, or thought about even if you know it deep down. I never really thought about how old the Adeptus Mechanicus actually is, for instance. I knew that the Emperor struck a deal with them before he had unified Terra, and yet it never occurred to me that this meant that they predate the Imperium. It's super obvious, but I'd never given it much thought.

A few different forge worlds (Lucius, Agripinaa, Stygies VIII, Graia, Metalica, and Ryza) are profiled, but they each only get half a page. It's great information, just don't expect too much of it. What I really love about these profiles, though, is how pro-Mechanicus they are. The whole book is written largely in service to the cult, and there's a positive spin on nearly everything. It's easy in Warhammer to get pretty cynical about your chosen faction and the Imperium (or Chaos, or Xenos, or whatever you're into) in general, and with good reason. Warhammer's a terrible setting. Everybody's wrong. But this is the army I'm spending hours painting, and it's the army I spend hours playing, so it's nice that the codex dedicated to it tells you how cool and powerful and successful it is. Many of the forge worlds, for instance, have a paragraph about a recent success against some threat, or some brilliant scheme it implemented to thwart an enemy. If I'm going to send this army into battle, I do want to be on its side. I want to believe it can win. I don't want to be thinking constantly about how beleaguered and ineffective the Imperium is. I want to know that the Adeptus Mechanicus can, through their faith in the Omnissiah, can clear the battlefield of the foes of humankind. And this codex does exactly that.

In addition to forge world profiles, there's a section on all the different kinds of troops (Skitarii, Vanguard, Ironstriders, Kataphrons, and so on) you're likely to find in an Adeptus Mechanicus army. It's narrative and provides no stats yet, but it does explain the ideas behind the various miniatures you've bought. This is the kind of thing you don't really need in a generic fantasy game, where an elf miniature is pretty much an elf, and a dwarf is a dwarf, and so on. But this is Warhammer. What the heck is a Kastellan robot? How are they different from, say, a Space Marine? How are they different from a Man of Iron? What is a Skitarii, anyway, and are the just Servitors in fancy clothes? All these questions and more are answered here. If you haven't had time to read the novels and watch the shows that explain these things, this is the crash course.

This section also explains common strategies of each miniature, too. A Sydonian Dragoon specialises in close combat, while the near-identical Ironstrider Ballistarii stays at range. Vanguards use radiation to scour the battlefield. And so on. Some of this is self-evident from the miniatures, others are entirely inconsequential aside from getting the lore straight in your head. You may never use any of it in a game, or you might try a few games where you adhere strictly to "historical" accuracy of your army. It's up to you, and either way it's fun to read about.

And speaking of fun reading, there are sidebars on several pages about "historical" battles involving the Mechanicum. They're no more than 4 or 5 sentences, but honestly they're some of my favourite parts of the book. Some of these may have whole novels dedicated to them, but as they appear in this book they're untold stories that spark the imagination and flood your brain with ideas for tabletop campaigns. They might seem like trivial flavour text to the casual observer, but flavour text can be priceless. I'll definitely be flipping through the lore section for these story ideas later.


After the lore, there's a few pages of painted miniatures. I'll admit that I thought this was a waste of paper at first, especially given how many professionally painted miniatures you can see these days on the Internet and White Dwarf. But the more I flipped through the pages, the more ideas the photos sparked.

I have some Kataphron Breachers, but I'd left off the front armor because, frankly, I spent way too much time painting the Servitor's torso to just cover it up with armor! And besides, I primed the front armor grey, but the rest of the miniature white, and when I tested some red paint over it, I was surprised that you could really tell. Seeing these photos made me realise, though, that the front armor plate doesn't actually have to be red. I can paint it Skeleton Horde to match the lower chassis, or black, or yellow with black caution stripes, or anything I want. Lots of ideas, now, and I think I may well add armour just to remind myself that they're Breachers, not Destroyers.

The gallery also shows where rank and faction markings go on most of the miniatures. I wouldn't have minded a little more clarification about this, but I've already put transfers on my infantry and some of my Ironstriders, so ultimately I'm probably better off not knowing what I got wrong. Still, it seems like a clear and authoratative explanation of all the iconography should be in this book, of all books, and I feel like they breeze past it pretty quickly.

Combat patrol and game rules

The rest of the book describes how Adeptus Mechanicus miniatures work in actual games, including a small Combat Patrol battle, a full-scale Incursion, Strike Force, or Onslaught modes (1000 points, 2000 points, 3000 points, respectively), and a Crusade campaign. What kind of information each section provides depends on what's relevant to the game mode.

The Combat Patrol section describes, very specifically, the 2024 Combat Patrol box. I didn't buy a Combat Patrol box because frankly I didn't care for the build of the army (I wanted Ironstriders and Imperial Knights instead of a Dunecrawler), and I don't intend to buy the new one for the same reason. There are datasheets specific to Combat Patrol in this book, though, so if I wanted to play Combat Patrol without owning the actual Combat Patrol, I'll have to adapt the rules provided for the "patrol" I actually own.

The rules provided for the three army types listed in the 40k rulebook feature special rules for the army, and detachments. A detachment is sort of a template you (figuratively) overlay onto your existing army. Once you declare your army to be a specific kind of detachment, you gain the collection of rules and strategems found in that detachment's template. It's essentially a way to change what tools you have available to you for a game. For example, the Rad-zone Corps grants your Adeptus Mechanicus miniatures the Stealth ability, while the Data-psalm Conclave allows a Tech-Priest to reduce an attacker's damage. You can read over the different detachments available, and pick one that matches the strategy or style of play you think you'd like to try.


After the rules come the datasheets. For every miniature Games Workshop has produced, and still supports, for the Adeptus Mechanicus, there are numbers. There's a number for movement (M), Toughness (T), Save (Sv), Wounds (W), Leadership (Ld), Objective Control (OC). There are numbers for each kind of weapon the miniature can possibly have been built with, and most importantly when there are several different kinds of weapons there's a photograph of what each weapon looks like! I don't think the datasheet card set has this, so this is a really important feature if you're still learning the different weapon types.


If you want to play Warhammer 40,000 as a campaign, with battles that tell a larger story, then you can use Crusade mode. This section provides goals and rules specific to the Mechanicum, many of which focus on, not surprisingly, Archeotech. With these Crusade modes, you can earn rewards and level-up your army as you play more and more battles.

I anticipate using these rules myself, and it's the one section I expected least in the book. I'm excited to use them, though, because I love a good campaign.

Data and more data

This is the first Warhammer Codex I've ever purchased or read, so I wasn't entirely sure what to expect. What I got has been almost entirely satisfying. I'm a little disappointed that there's no section just about weaponry and armor and gear. What's an auspex? What's that button on a Skitarii's backpack do? What do they keep in that little leather pouch? I'd have loved a section about the gear, but all this book provides is a (much appreciated) photo of each weapon as it appears on a miniature. I appreciate the functional data, but I wouldn't have minded getting some weapons lore.

Then again, maybe a weapons and gear book will eventually be released. Or maybe several have been released over the years, and I just need to hunt down a used copy.

The benefit of leaving stuff out of the book, however, is that the book is only 120 pages. That's a big deal for me, because I have a lot of game books, and they do tend to feel pretty heavy in the backpack after a while. I'm happy that I can play my army with just this 120 page book instead of, say, a 230 or 360 page book!

Header photo by Seth Kenlon, Creative Commons cc0.

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