I really can't wait for this series. I especially want to see how ADB handles how the various characters of the traitor legions put all their issues aside (especially after the legion wars in the Eye) to create the Black Legion. How does Abaddon convince the others to form a new legion around the remnants of the "cowards" who fled Terra. Not to mention how the marines of the various legions interact with each other. I can't imagine the former Iron Warriors and Emperor's Children, for example, would get on very well after the events of Angel Exterminatus.
The human appendix. Proof of a higher power. A divine kill switch so to speak.
No one really likes a smartass, but people tend to like a dumbass even less.