So the sixth book in the series is out. Should be good, it includes the 'black sheilds', marines from Legions now in Horus' army who remain loyal to the Emperor. Which sounds like a great idea for an army.
This link to the FW page has the obligatory little you toob clip.
I'm imaging using all of those kool WE, SOH, DG and NL heads on my betrayal of Calth marines to make a kool but battered looking army (yeah, I can count, I know, I know).
But hey, it's not like I have a 30K army...