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Liber Mechanicum Review – Warhammer The Horus Heresy

Hosts of robotic machines and cybernetic soldiers armed with arcane and esoteric weaponry march upon their enemies as the forces of the Taghmata Mechanicum, Questoris Households and even the mighty engines of the Titan Legions get their rules for the new edition of Warhammer The Horus Heresy in Liber Mechanicum, up for pre order today!

In this post we will be diving into the new Forces of the Omnissiah Army Book with our Liber Mechanicum review. We’ll be checking out how the army is constructed, taking a look at the units and talking about the 3 army lists contained within.

Massive thanks to Games Workshop for sending us a free review copy of Liber Mechanicum to review and investigate prior to release! If you would like to support the site then why not order your copy of Liber Mechanicum through our affiliate Element Games and save yourself money too.

We have also done a full review video to accompany this written post, which you can check out below or over on YouTube

So make your pledges to the Ominissiah and ready your Maniple, the forces of the Mechanicum are going to war

Liber Mechanicum Review

This summer we saw the well received 2nd edition of The Horus Heresy drop, and alongside it we got both of the supplements allowing you to play one of the 18 Space Marine Legions. Games Workshop shared that volumes for the other factions of the Horus Heresy would follow relatively quickly, and today Liber Mechanicum is up for pre order which contains the army lists for the Forces of the Omnissiah.

It’s worth starting here with the fact that this book actually contains 3 different army lists – The Tagmata Mechanicum (The fighting forces of the Mechanicum, think cybernetic soldiers, robots and deadly vehicles) The Questoris Households (The Knights of the 31st Millennium) and the Titan Legions (The mighty god engines of the Adeptus Titanicus). This book also contains the “Standard” variations of these forces – while the traitors went down a different path during the Horus Heresy and eventually became the Dark Mechanicum, this book contains rules for the forces at the very dawn of the Horus Heresy. Traitor players do not need despair though, as we do get a number of profiles for named characters than pledged for the Warmaster, but the makeup of their armies is very much in line with the orthodox Mecanicum at the time the Heresy erupted. We do get a nice tease that future supplements may contain an alternate army list for the more “unusual” offshoots of the Mechanicum once they had fallen to Chaos…

As with the other Liber volumes, The Mechanicum army list uses the same Crusade Force Organisation Chart as used by the Legiones Astartes, however both the Titan Legions and the Knight Households also have their own Org Charts that we will talk about a little later in the review. We also get reference to Core and Expanded lists again, essentially this means that any profiles related to models that can no longer be purchased will be included in a PDF on Warhammer Community and will still be fully “legal” to use in games – basically this book just contains units that can be purchased, while more unusual stuff that may be from existing collections or new units that may require conversion can be downloaded.

A nice thing about starting a Mechanicum force is that you could use it as an allied contingent to an Astartes force – you can simply pick up a HQ and a Troops choice and use this in conjunction with an existing force as you slowly grow it in size

Warlord Traits and Advanced Reaction

In the book we get a trio of Warlord Traits:

A Soul of Cold Iron allows friendly units within 6″ to still move and charge while pinned but only make snap shots. In addition they get to make two reactions in the movement phase

The Logic of Victory gives the player an extra reaction in each phase of the following turn as long as the warlord did not shoot or was engaged in combat. It also gives the unit they join +1 WS and BS and +3 I and M when making reactions.

The Science of Slaughter gives the Warlord a cumulative +1 WS and S each turn they are locked in combat after the first one. While this resets once the combat is over, this can give an Archmagos some bite in a prolonged combat!

The Mechanicum Advanced Reaction is really interesting, when a unit targets a unit containing any independent character, all Mechancum units within 12″ can fire back at them before the shots are made! This is amazing, just keep in mind that any Automata units are not eligible to make reactions, and so Castellax and Thanatar cannot take advantage of this (Though later in the book there is a way of enabling this…)


We get 4 HQ options, a Loyalist character and 2 further traitor characters in the appendix.

Each army can take a single Archmagos and this can be taken either on food or on an Abeyant – each of those options is a 0-1 choice, and the Feudal Hierarchy rule stops them from both being taken together. The main difference between the two of these is an extra pip of toughness and 2 extra wounds on the Abeyant, which also gets the Antigrav rule. These are your praetor equivalents and can take a stack of different weapon options to tool them out for battle. Your Archmagos also gets to pick a high Techno-Arcana – These are extra special rules that add some more flavour and very often add additional army construction options

Archimandrite – Allows a Mechanicum allied detachment to be taken alongside the primary one, and then using Battlesmith rule they can pass their BS to the target or grant Power of the Machine Spirit

Cybernetica – Possibly my favourite, it allows you to take Castellex as Line and makes them reduce cover saves by -2. In addition friendly Automata can take wounds for the character even if they are allocated using Presicion Strikes or Sniper

Lacyraemarta – Makes Rending, Poisoned and Fleshbane only trigger against the character and their unit on a 6, and also allows Battlesmith to be used on Infantry

Macrotek – Allows Tech Priests to be taken as a Troops choice, allows Battlesmith to be used on buildings, and also allows the player to move 3 terrain pieces before deployment!

Malagra – Allows a Arcuitor Magistratum to be taken as a HQ choice, and allows you to have 3 bought within the same unit (Usually these are a 0-1 choice)

Myrmiidax – Allows a Thanatar to be a HQ choice and unlocks Myrmidon Secutor as a Troops choice and Myrmidon Destructors as Elites

Reductor – Allows Battlesmith to be used against buildings to cause damage, and at the start of the game the player can pick 3 terrain pieces to grant no cover and become difficult and dangerous terrain to represent a pre battle bombardment

We also get an option for a Magos Dominus and one on Abeyant, these are essentially your Consul level character which again have options for weapons and act as support with Battlesmith for example

All of these units also get access to Cybertheugy, which in practice works very similarly to Psychic powers, essentially this is a list of different abilities that are normally triggered in place of making a shooting attack, with bonuses such as allowing Battlesmith to trigger twice, allowing units to move in the shooting phase, or unleashing a particularly fancy weapon.

Calleb Decima Invictus is a Loyalist HQ option with a Archmagos profile who has a unique warlord trait that allows units within 6″ to move through cover.

Archmagos Draykavac is a traitor HQ option who is really cool, friendly units within 12″ can choose to remove a single model from their unit to negate the effects of pinning, and he is armed with a particularly brutal weapon where you roll 2D6 and subtract the targets toughness, with the target then taking that many wounds at AP2! he can also be taken as a Troops Choice in a Questoris army, and unlocks Castellax and Vorax to be taken as troops!

Archmagos Anacharis Scoria is the final traitor HQ and he is rocking a primarch level statline, a stack of wargear and special rules, a weapon that strikes at S10 AP2 with Armourbane, Exoshock 4+ and Murderous Strike 5+ and finally a unique warlord trait that allows automata within 6″ to make reactions – combine this with the Mechanicum Advanced Reaction and it very quickly becomes a very bad idea to shoot Scoria when all Castellax and Thanatar near to him can shoot you back before you get to roll any dice! An excellent choice for a traitor force!


Tech Priests are our first Elite option, and can be equipped for a number of different roles, either acting as a Battlesmith unit to patch up our units, to improve the feel no pain of Thralls or to smash things up with Sunder and Wrecker

Arcuitor Magistraerium are a new Loyalist only unit that are assassins used against tech-heresy. Decent combat profile and some great weapon options and the Monster Hunter rule – I look forward to seeing the models for these! Only a 0-1 choice however so no spamming potential!

The Domitar is pretty tasty at T7 and 5 wounds, fulfils a similar role to a contemptor at a lower points cost, however the weapons do not have brutal so are better suited to bullying infantry as they can be taken in units of up to 5

Myrmidon Secutors are a great shooty unit, with T6 and 4 wounds each plus a refractor field they can take some shifting while also packing some awesome weaponry – for example you can give each of them 2 Phased Plasma Fusils for a total of 6 shots each at S6 Ap3 and Breaching 4+ Excellent at shifting Marines off objectives


Our troops options match those in the first edition of the game, though there are a couple of tweaks here and there

Tech Thralls have dropped to strength 3 but now boast 2 shots each on their las locks and have Feel no pain 5+ (Improving to 4+ if near an upgraded Tech Priest)A for a bargain 45 points for 10, they can take up to 20 more in the unit and if they number 20 or less can take a Triaros as a dedicated transport – These guys get Line

Thallax have dropped to S4, but have also dropped in points to 125 for 3, their jetpacks are ace increasing their movement to 14 and allowing them to make an additional 6″ move after shooting – Also a Line unit making them VERY good at hopping ahead early game to claim objectives, especially if you make them a unit of 9. They also now get Feel no pain 6+. Despite all the hype for Castellax, I honestly think this is the unit to watch

Scyllax are an aggressive Line close combat unit with toughness 5 and 2 wounds making them surprisingly resilient, in combat they always wound one lower than usual – for example if they would need 4+ to wound they would instead wound on a 3.

Everyone’s favourite big chunky robot the Castellax is back, but sadly is not Line unless taken with a Cybernetica Acrchmagos, but they are still very good – toughness has gone down a pip to 6, however Strength has increased to 7. With 4 wounds each these are a great unit to sit on objectives (If you take Cybernetica) and are a scary threat to see on the battlefield as a troops choice – beware however, Dreadnaughts will cut through them like butter due to Brutal!

The Triaros Transport is much the same as it used to be with an impressive 14/12/12 armour and Flare Shields as standard, but has gained an extra hull point and can now carry 22 models – certainly going to be tough to chew through and should keep your units safe until they get to their target

Fast Attack

In the fast slot we get the Arlatax, which is essentially a refitted Domitar with a jump booster giving it movement 12! With Breaching on its power blade arrays hitting at S7 this will scare units with its large charge threat range

In a similar role we have the Ursarax, which while slightly weaker at T5 and 3 wounds each are infantry and so can do reactions. They also have Feel no pain 6+ and duel Lightning Claws or Power Fists – again equipped with a jump booster they can hop 12 inches per movement phase and get the M12 bonus to their charge distance too

As a cheap Scout unit we have the Vorax, clocking in at 65 points it can scout ahead and harras things with its lightning gun and rotor cannons. Plays a similar role to a land speeder squadron

Finally we have the Vultarax, these are insanly quick at M16 with their Stratos Thrusters and armed with an Arc blaster each these are our secret weapons against Dreadnaughts and vehicles – each wound of 4+ automatically wounds a Dread or causes a glancing hit on a vehicle meaning a unit of 3 can reliably take out most vehicles unhindered.

Heavy Support

Our equivalent to the Leviathan Dread, rocking T8 and 7 wounds along with a 2+ save and a Atomantic Deflector the Thanatar is a great choice – it can be equiped with a range of different weapons suiting it to a number of different roles on the battlefield

The Myrmidon Destructor take everything that is great about the Elite version and straps some even more powerful weapons on them such as Conversion beamers or the amazingly named Darkfire cannon

The Karacnos Assault Tank not only looks beautiful, but it also a great tank – with 14/12/12 and Flare shields as standard it will take a beating, and the main weapon a S6 7″ blast weapon with Fleshbane, Rad Phage, Pinning, Shell Shock 3 and Crawling Fire for when you absolutely positively need to pin a target or two

Both Krios tanks have now been folded into a single profile with a 25 point upgrade to the Venator Tank Destroyer version. Very quick at m16 however is a little more fragile than other Mechanicum vehicles at 13/12/10 meaning bolters can hurt you from the rear. The 5″ blast Lighting cannon will shred infantry on the standard version, while the Venator gets a 4 shot lascannon that causes pinning

We also get a surprise in the Heavy slot with the Knight Moirax! With up to 4 in a single heavy slot this gives you a T7 6 wound armiger armed with a selection of decent weaponry without having to eat into your super heavy allowance. I’m looking forward to getting a selection of weapons to fill a single slot – as each of the armigers gets to act independently after deployment

Lords of War

In the Lord of War section we see a variety of Knights, the Magaera, Styrix and Atrapos representing the Mechanicum variants of the Knights with 13/12/12, Flare Shields and 8 HP they will take some killing, they also have Ion shields which grant them a 4+ inv save against shooting to the front and 5+ to the sides. As you can imagine these dont come cheap ranging from 400 to 500 points.

We also get Acastus Knight Asterius which is slightly harder to crack open at 14/13/12 and 9 HP – Stand this over 48″ away from a target and the two twin linked Heavy Conversion beamers are throwing out multiple 5″ S12 AP 1 pie plates!

Both Ordinatus Engines are also represented in the book, they are not cheap with the Ulator not even being able to be taken in a 4000 point game, however they are ridiculously destructive. The Akateus has a 42 transport capacity and can use it’s massive drill to do a subterranean assault, while the Ulator fires a 5″ blast marker that moves for 72″ away from the gun hitting everything the template travels over for destructive hilarity. Realistically you’re not going to be using this in a normal game, and is probably better suited for a one off scenario!

The Titan Legions

Included in the book is a Titan Legions army list, and we actually get a new force org chart for them. While you can take any of the Titans in a LOW choice for any army, you can also take an entire detachment of them. This consists of a compulsory Lord of War of Troops choice and up to 2 optional HQ, 6 Troop and 3 Lord of War slots. This detachment itself is also an optional detachment meaning it can be taken alongside a primary Mechanicum detachment for example, but unless you are playing a narrative mission this is quickly going to eat into your LOW allowance unless you are playing a VERY large game. Again, like with the Ordinatus I’d probably make sure your opponent knows you are planning to bring the Adeptus Titanicus so they can build to face them, this certainly isn’t one for a random pick up game!

We get a new HQ option in the form of the Secutarii Axiarch who can transmit one of 4 orders to all Secutari on the battlefield – granting them Feel no pain 5+, Move through cover, Wrecker or Preferred Enemy Infantry – this is picked after deployment and is gained by all Secutari

Both flavours of Secutari are included as a troops choice though do not have line – meaning that technically a Titan legion army will not be able to win games as they cannot take objectives! Again, I think the intent is here that Titans are used for big showcase games, and as such they will be running alongside a primary Mechanicum army – This is as it should be and makes sure the place for these Engines is in massive games running into the many thousand of points.

The Titans themselves are very similar to their old rules, with the Reaver and Warlord going up in points and the Warhound still viable in a 3000 point game as your entire Lord of War allowance. HP has gone up across the board though meaning that the Titans should stick around a little longer than they used to. The Warbringer Nemesis also gets a profile, but again realistically you’ll only be taking one in an 8000 point game!

Questoris Households

The final army list in the book is the Questoris Households. While the Titans are very much designed to be fighting alongside another primary force, the Knights can be taken as either an primary force rather than a crusade org chart, or be used as an allied optional org chart. You can of course also take single Knights as a Lord of War choice alongside another army. When taken as a Primary force any Knights taken from the army list do not count towards the Lords of War cap, allowing you to take a full army – this also allows you to take another Lord of War (Such as a Titan) alongside them!

People with existing Knight forces may have to pick up some more units to be able to use them as an army however – For each Lord of War you take within a Questoris army you have to take 2 troops choices – with a single Armiger Warglaive or Helverin counting as a troop choice each. Basically this means 1 in 3 models in your force can be a “big” Knight with the Armigers acting as the bulk of the force. Amazingly, Armigers have Line meaning that even a pure knight force can compete and still win games against other armies! At T7 and 6 wounds they are similar to a Contemptor and adds some elements that even bolters can threaten – which was perhaps the worry for Games Workshop when creating the army list – even if you can’t scratch the Knights themselves you can still take out the Armigers and stop the Knight player from scoring.

All of the other varieties of Knights not seen in the Mechanicum list are here, including an option for a generic Knight Questoris that can build any of the variants from the plastic Knight kit. This is great as allows players to make a legal Questoris Households army just using plastic kits – but still having the awesome options for the resin Forge World models. While Knight players will have to buy 4-6 Armigers to make their army 2nd edition legal, I do think this is a good change and ensures that both players are going to have fun when facing Knights.


So what do I think of the new Liber Mechanicum? I am a big fan of the Mechanicum and have a growing collection of Titans and Knights, so I was happy to see this come so soon after the core Marine books. The Mechanicum in 30k have some brilliantly diverse models with some real character, and are a great painting and hobby project, along as a formidable force on the battlefield with these new rules! If you have an existing Mechanicum army you’ll be able to port over to 2nd edition with minimal effort, while some point have shifted on the whole you wont be too far away from your old army. Knight players will need to pick up a couple of couple of armiger boxes, but honestly I think this is a good change that levels the playing field when facing Knights. I’m also excited at the teases that varient lists such as the Dark Mechanicum could follow that add some of the really weird and wacky stuff that we have heard about in the lore but not yet seen in the game.

If you want a little hobby project, the fact you could start a small Mechanicum army with just a HQ unit and a troops choice or 2 as an allied element to your Marine force is also great, and could give players a little variety if they want to expand upon the contents of their Age of Darkness box. Likewise, lots of 40k players who have Knights can now easily slot one into their existing Heresy armies too without any Armiger restrictions seen in the pure Questoris force.

We know we are getting another book in a couple of months covering the Imperialis (I suspect this will be the Warp Cults, Imperial Army and Militia lists) and hopefully those armies that are a little further behind such as the Daemons of the Ruinstorm get their PDF soon allowing players to use their existing armies in the meantime.

The other exciting thing about this book is the fact that we might just see some of these units changed to plastic in the future, making creating a Mechanicum army much more affordable – while we don’t know this is coming for sure, I’d be very surprised if Games Workshop stop at just making the resin Space Marine units.

Warhammer The Horus Heresy is possibly my favourite Games Workshop game at the moment, and I can’t wait to see what the future holds for it!

Liber Mechanicum is up for pre order today and is released on Saturday 20th August

Games Workshop provided Sprues & Brews with a free copy for review purposes.


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