User blog comment:Legionaire22/My first real AT Idea/@comment-3258762-20130723213251/@comment-3258762-20130724130922

But lets look at what we have here

We have Dorn in command of Terra. Terra is one hell of tough nut to crack, even without the rest of the Sol System.

Then we have Corax leaping about and causing damage, stopping resources from coming along and the like.

Then we have the Space Wolves, who are currently the biggest legion (Yes, at the end of the Great Scouring, the SWs were larger than the Ultramarines, who lost extreme amounts of their forces during the battle of Calth) And yes, the SWs and the DA will have a fight, because Russ notices how weak the DA are, not the other way around (It is not decided who will win that fight)

Then we have the Blood Angels, of whom all Successors would return to them, bringing about the BA Legion again.

Then we have the White Scars who, due to their fast-attack tactics, did not suffer that much damage during the Siege of Terra.

Meanwhile, Roboute has

An incredibly understrength legion of Ultramarines

Half of the original Dark Angels legion

The nearly non-existant forces of the Salamanders

And the slightly schisophrenic forces of the Iron Hands who, if the traitor legions join up, will ditch Guilliman.

What of the Traitor Legions, then?

Well, Abaddon is having some trouble getting the forces of the Black Legion to heel, he does not have the time to assert his dominance as he did in the original timeline. Not to mention the BL are pretty weakened but not the weakest.

Angron will not help anyone, he will just kill and maim and murder. Without Lorgar (The two became good friends when Angron acended to Daemon Prince status) to reign him in, he will rampage across the galaxy, causing as much harm as good to Guilliman

The Death Guard took the most damage during the entire Horus Heresy and, without any normal planets left, would find themselves incapable of fixing up these losses other than by corrupting other marines. Which they can only do if they actually get close enough to them.

The Night Lords primarch refuses to act at all, and only a small portion of the NLs can actually do anything. If anything, considering how Konrad felt so bad for partaking in the HH, he would probably try to help the Dornians rather than the Guillimanists. But he won't, he's depressed :3

Fulgrim and his legion, as stated, will not leave the Warp. They have done enough now and now they want to enjoy the realm of Slaanesh instead.

The Iron Warriors are the only ones who can prove a real threat, but they too are understrength and weakened, and remember: The Iron Cage has already happened, so the Imperial Fists and Ultramarines both have a hatred for them.

The Thousand Sons are probably the weakest of them all right now, they were nearly exterminated during the Burning of Prospero. They will most certainly just remain in the Warp and bide their time.

And finally, we have the Alpha Legion. And can anyone really say Guilliman would accept their help?