While the Space Marine Legions take up much of the press around the Horus Heresy – being genetically descended from the Emperor of Mankind is some exceptional nepotism – the Great Crusade was supported by the massed armies the Excertus Imperialis, a vast force of human, and abhuman, soldiery.
Within their ranks the Solar Auxilia were formed, elite soldiers trained in the Sol System, the cradle of mankind. When Horus flipped, the Solar Auxilia operating alongside the Legions also had to make the fateful decision of which side of the war to fight on.
Sent to the battlefront as mighty formations known as Cohorts, a Solar Auxilia force is a mighty military behemoth consisting of everything needed to wage war from gigantic fleet voidships to mobile crew-served infantry support weapons. Each Cohort is further divided into Sub-Cohorts which are assigned to particular battles, and in Legions Imperialis this is often the force at your command.
Solar Auxilia Special Rules
Unlike their tall, ceramite-armoured allies (and enemies), the troops of the Solar Auxilia are not entirely self-sufficient during battle. Their vast armies rely on commanders to orchestrate them, and units with the Chain of Command keyword cannot receive orders other than Advance unless within the sphere of influence of models with the Solar Auxilia HQ special rule.
Legate Commanders have the widest aura of command, but you are limited to one per 1,500 points. They are backed up with Auxilia Tactical Command Detachments and Tank Commanders, who project smaller auras.
Numbers will tell against even the mightiest power-armoured troops, and the press of bodies presented by even the elite Solar Auxila’s Close Formation Fighting grants them extra CAF when fighting shoulder-to-shoulder or garrisoned with comrades.
The Forces of the Cohorts
The traditional Solar Auxilia army is built around a core of elite yet alarmingly expendable Lasrifle Tercios, whose Line keyword grants them an extra 2 Tactical Strength when deciding who controls Objectives, which are the key to winning games.
You can fatten these Detachments up with flamer-toting Auxiliaries, and add power weapons with Veletarii and Charonite Ogryns, which benefit from the Rend rule – letting you add D6 to your Fight rolls, to a maximum of 6D6.*
While massed infantry is helpful for securing objectives, tanks are good at shooting things off them. Solar Auxilia Armoured Company Formations ensure that you can field big scooped handfuls of the things, with a Tank Commander to boot.
You’ll fill your Battle Tank Detachment slots with either Malcador or Leman Russ Squadrons, the latter of which can contain up to 10 vehicles. Take the Vanquisher variant of the Leman Russ and you’ll get the Armourbane trait on its shooting attacks, which forces rerolls for successful saving throws made by Vehicles, Super heavies, Knights, and Titans.
While it might look like a straight upgrade over the trusty Leman Russ Battlecannon, its Anti-tank trait reduces its AP value to zero against Infantry and Cavalry models. By contrast, the heavy bolter is Light, so it simply bounces off Vehicles and bigger targets. As Detachments generally have to fire at the same target, matching your loadout to the target is vital.
Auxilia-Super Heavy Tanks Squadrons fill your Heavy Armour slots, covering a variety of armament patterns we know as Baneblades and Hellhammers.
These rolling fortresses are spoiled for choice with weapon options, and every bit as tough as a Legion Kratos. They bristle with Point Defence weapons, smaller guns which grant some flexibility to these lumbering beasts.
These may be fired on a Secondary Target, and may also fire in the Movement phase if the Detachment has been given an Advance or March Order – a helpful infantry deterrent.
The Auxilia also have air support in the form of the Thunderbolts and Marauders of the Aeronautica Imperialis, as well as dozens of guns in the form of Tarantula and Rapier Batteries that can help even the odds against the Legiones Astartes.
* Tactical Marines can do similar, which is why you may occasionally see Terminators palling around with regular Astartes.