Legions Imperialis – Adding a Legio, Knight House or Auxilia to your Traitor Legion

And of course, we have to complete the list of all 18 Legiones Astartes by adding those who pledged their allegiance with the Warmaster Horus. And they wouldn't fight alone, not only with other traitor Astartes, but other parts of the former Imperial warmachine.

The listing is a point to begin with, based upon my research in the wikis and Horus Heresy community. The list of allies will probably grow over the product schedule and campaign supplements for Legions Imperialis. While in case of the Collegia Titanica, the Legio Mortis fought along side every Traitor legion of the Astartes, and the only known titan legions who fought alongside the Night Lords, other flexible options are the Legio Fureans and Legio Krytos, who fought with every traitor legion with the exception of Konrad Curzes troops. Further more the support of Traitor Solar Auxilia, Renegade Militias and the Dark Mechanicum was not infrequently.

The 3rd Legion, Emperors Children, first to bear the Emperor's personal standard.

Legions Imperialis – Adding a Legio, Knight House or Auxilia to your Loyalist Legion

In Legion Imperialis you have the opportunity to use combined forces, so not just Astartes but field them with support of Knight Households, Titan Legios and Imperial Militias or Auxilia regiments. But which Legiones Astartes fought alongside which of those and what would create a proper alliance according to the lore?

Of course, you can do what you want, it is your hobby, but with the Horus Heresy community known for being fluff bunnies, this is something I wanted to share with you, based upon lists from the fan wikis and combined work by people like David from Cat Hair in the Paint Pot.

I merged the lists and linked the according information from the wikis, so you have it at hand by looking up your Legiones Astartes. Beginning with the Loyalists. With the exception of the Raven Guard, every loyalist legion fought at one point along side the Legio Gryphonicus (War Griffons) and each of them can use the Solar Auxilia without any doubt.

The 1st Legion, the Dark Angels from Caliban, already have the opportunity to bring their troops in Black, Green or White, but are able to field an even broader variety with the following affiliated factions.