Today we are joined by the Arch-Traitor James, one of the playtesters on the new edition of Warhammer: The Horus Heresy. He’s here to explain why it’s so good to be bad…

We’re here to defeat the Emperor and we’re going to use whatever tools we have to do it. The standard conventions of war are out of the window if you’re playing Traitors, you have access to Warp-fueled technologies and powers to enhance and bolster your army and guarantee success.
As the course of the Heresy progresses, the Loyalists and Traitors start to diverge in tactics and even troops. The Emperor's Children and World Eaters are the first to see big changes, and they both get two Rites of War each: one representing their forces in the earlier years of the Heresy and another representing their corrupted incarnations as the civil war draws to a close.
Rites of War
With the core rules changes, a number of the Legion Tactica have shifted too. One to watch out for is The Nail’s Bite for the World Eaters. It’s a massive game-changer, letting you tap into the uncontrollable frenzy of the XIIth and channel that rage towards any unfortunate Loyalists who might be within axe range.

The Nails’ Bite
World Eaters Legion Tactica
Deep under the effects of their invasive neural implantations, the World Eaters became heedless of conventional military strategy and often ignored the logical goals of battle in favour of debased violence and the chance to cause blood to flow – from whom it flowed was often a secondary consideration.
The Controlling Player may choose that a World Eaters Unit becomes Lost to the Nails when it fails a Leadership Check.
When a Unit entirely composed of Models with this Special Rule fails a Leadership Check, that Unit’s Controlling Player can choose for that Unit to become Lost to the Nails.

Lost to the Nails
When a Unit becomes Lost to the Nails, all Tactical Statuses affecting it are removed. In addition, while a Unit is Lost to the Nails:
Models in that Unit may add +1" to the distance of any Set-up Move.
Modify the Attacks Characteristic of Models in that Unit by 1+
Models in that Unit are considered to have Leadership, Cool and Willpower Characteristic of 10 (unless it would normally be higher).
If, at the start of the Controlling Player's Charge Sub-Phase, the Unit is within 12" of any enemy Models, that Unit must make a Charge Move. If more than one enemy Unit is within 12", the Controlling Player of this Unit must select the closest enemy Unit as the Target Unit for that Charge.
At the start of the Controlling Player's Charge Sub-Phase, if there are no enemy Units within 12" of a Unit that is Lost to the Nails, that Unit is no longer Lost to the Nails.
If melee combat isn’t your thing, look no further than Perturabo and his new Gambit, The Breaker. Should a champion of the Emperor have the gall to challenge him to a duel, the Primarch can simply signal to a nearby unit to gun the arrogant whelp down instead of bothering to raise his own weapon.

The Breaker
Iron Warriors Gambit
Perturabo rarely entertained notions of honour in battle, instead seeing only the mathematics of slaughter. Even when an enemy champion sought to engage him in honourable combat, Perturabo was often inclined to direct his forces to gun down his foolish opponent instead of sullying himself with dispatching them himself.
This Reaction allows a friendly Unit to make a Shooting Attack targeting a Model that Perturabo is in a Challenge with.
The Breaker: This Gambit can only be selected during the first Face-Off Step of a Challenge. If this Gambit is selected, this Model does not make attacks during the subsequent Strike Step. Instead, this Model’s Controlling Player can select a single friendly Unit composed of Models with the Iron Warriors Trait that is within 12" of any enemy Model in that Combat and not Locked in Combat and make a Shooting Attack with that Unit. All such attacks are resolved as Snap Shots with the exception that Weapons with the Blast (X) Special Rule or the Template Range Characteristic may not be used, and wounds from this Shooting Attack can only be allocated to the enemy Model in the Challenge.
Night Lords players will quickly notice that Night Fighting isn’t in the Core Mission Pack any longer. But worry not, the addition of Tactical Status now brings previously overlooked options right back into the game. Nothing feels better than proving your superiority by using heavy flamers and your widespread access to the Fear (X) special rule to Panic your enemy, then stride up to them and score an Objective they thought they controlled whilst they cower in your very presence?
I’d be remiss if I didn’t mention the changes to cover. Medium and Heavy Cover allows your Traitor Legions to run the gauntlet towards their Loyalist foes more safely, blocking line of sight between their guns and your forces. What better way to make use of this than with the Better Part of Valour Advanced Reaction, letting you melt away into cover should an enemy want to charge you, ready to continue terrorising the enemy next turn.

Better Part of Valour
Night Lords Advanced Reaction
While other Legions swore oaths to never take a backwards step, the warriors of the VIIIth Legion took a much more pragmatic approach, holding self-preservation above notions of honour.
This Reaction allows a Unit to Fall Back when it is the Target of a Charge.
Trigger: The Reactive Player may declare a Better Part of Valour Advanced Reaction during Step 4 of the Charge process of any Charge declared by the Active Player that targets a Unit which only includes Models with the Night Lords Trait.
Cost: The Reactive Player must spend 1 point of their Reaction Allotment to declare a Better Part of Valour Advanced Reaction, this cost paid as soon as the declaration is made.
Target: The Target Unit is always the Unit whose Charge triggered the Reaction. The Reacting Unit is always the Unit that was declared as the target of the Charge that triggered this Reaction.
Process
Once this Reaction is declared, the Reacting Unit must immediately make a Fall Back Move as if it was affected by the Routed Tactical Status
Once this Fall Back Move is completed, the Reacting Unit does not gain the Routed Tactical Status
Standout units
My favourite Unit so far is the Thousand Sons Saturnine Dreadnought and taking one of these with the Pavoni Prosperine Arcana is great. At the cost of a Reaction Point, you can use the Stoneform Psychic Reaction to give the model +2 Toughness for the remainder of the Shooting sub-phase, making it a mighty Toughness 10. Add to that its thermal diffraction field and you have even lascannon and multi-meltas wounding it on 6s. This is great until Perils of the Warp inevitably removes its last wound and it explodes… but at least it goes out doing what it loves: channeling uncontrollable amounts of Warp energy.
Next I’d have to go with Ashen Circle from the Word Bearers, whose role on the battlefield is clearer than ever before. This unit steers hard into the new Tactical Statuses, with their Akkadic Hand Flamers causing Panic (2), hitting opponents with the Routed condition even before you charge them – almost guaranteeing you Victory Points from their Vanguard (3) Special Rule if the enemy is on an Objective. Their Axe-Rakes are nothing to turn your nose up at either: Phage (M) hamstrings enemy units you wound for the rest of the game!
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My favourite thing about this edition is the army composition – the variation of armies we’re going to see on the tabletop is going to be unparalleled. Yes, you can take loads of multi-melta armed Heavy Support squads, but you’re probably going to lose to someone bringing loads of Tactical Marines. There's such a variety of ways to approach winning that I’ve found it impossible to write an army list that looks unbeatable. Expect to see a much wider variety of themed army lists coming to a table near your very soon.