As I'm building this army, I'm sticking very hard to a theme. I feel very strongly that if I'm going to play a 'bad-guy' army, I'm gonna do the guys that started it all. In addition to being renegade Space Marines that have found the glory of daemon-worship and summoning rituals, the Word Bearers also happen to be the arch-nemesis to the Ultramarines chapter- a perfect example of faith versus format, zealotry versus stubborn-ness, evil versus good, and even good 'ol red versus blue.
The Word Bearers are very well-known for their absolute worship and subservience to the Dark Powers, specifically summoning daemonic creatures and possessing brave warriors. They are also the only 'Legion' left in the renegade marines, waging war insanely but as overwhelming as they were 10,000 years ago. Although the XVIIth Legion is massive and widely-known, they do not like to utilize 'marked' troops or allies from other warbands. It's not that they are full of mistrust for others, it's actually more that Word Bearers follow the great plans laid out by any number of ancient Daemon-lords and rarely do warriors from other Chaos Marine forces understand.
Those two things are the guiding principle here- lots of possessed stuff and no marked troops. I know this doesn't make for a very competitive army, but that's not how I think. I want Word Bearers to be represented, and some butt will get kicked for it nonetheless. Here's the army list:
Chaos Space Marines, 750 points
Kor Kharsis, Ascended
Daemon Prince, wings 
the Horns of Faith
Chaos Squad (10), Aspiring Champion, Pwr Fist, Plasma Pistol, Plasma Gun, Missle Launcher, Icon of Chaos Glory 
the Flames of Faith
Chaos Squad (10), Aspiring Champion, Pwr Swd, Plasma Pistol, 2 Flamers, Icon of Chaos Glory 
|Kor-Kharsis leads his force on a raid... FOR CHAOS!!!|