Wow, I need to pay more regular attention to this thread. Chaos player here! Yes, Dark Vengeance chaos forces are meant to be Crimson Slaughter based on the included fluff. Truth is, in spite of the fact their color scheme is lots of reds, they aren't Khornate. They're actually a renegade faction that's been possessed by daemonic forces and all sorts of nasty spirits. They are not devoted to any one particular chaos god at all. If you're interested in going down the Chaos Space Marine rabbit hole, go ahead and pick up the Crimson Slaughter supplement while you're at it. It's fantastic, especially compared to the disappointing Black Legion supplement. (I painted my army Black Legion colors :( ) Black Legion kinda has rules going every which direction, but Crimson Slaughter is heavily melee-centric. The central focus on one thing makes it a lot more useful in my opinion. If you want to sprinkle a little range, you can have a separate detachment of standard CSM's or even go nuts with Daemons.