This book informs players of the wargame Warhammer 40K of the evil forces of Chaos who have betrayed mankind, it is set out perfectly and includes all the information needed to start a Chaos army
Probably the weakest of the Chaos Space Marine Codices. There were a lot of good concepts for future Chaos units, such as Raptors, Possessed and Obliterators (that would flesh out in later Codices to be pretty good), but it seemed that it never went the distance to create the Chaos variety you got with earlier and later codices. I also felt that the rules for Greater Daemon summoning were a big points sink for what ended up being a gamble (you could lose a high point model to the daemon's arrival and it might be way out of position to be effective)- but I guess that was the fickleness of the Chaos Gods.