Codex: Horus Heresy
A few more rumours for you on this interesting little (rumoured) Codex.
It will apparently be a reversal of the Armageddon 3 'Good Armies' 1 'Bad Army' idea and will feature 3 Traitor forces and a single Imperial Army.
The Iron Hands are rumoured to be the other Imperial Choice, although some might see this as unlikely as the World Bearers (Is this Word Bearers or World Eaters?) and Iron Warriors seem to have been picked for two Traitor forces. The third traitor force may be a 'Rebel Imperial Guard' list, that has Demagogues replacing Preachers and Cult Masters as Commissars. Other units may even include Beastmen. Nothing more than a rumour? We'll have to see...