Now I know that the new Imperial Knights Codex has a new allies matrix addition where they can not ally with an army that belongs to the Chaos Powers - treated as Come the Apocalypse.
But if you ally them with a Guard army force, in this case Traitor Guard using the Imperial Guard Codex, and the Guard ally themselves with Chaos Marines that are kept on the other side of the table (House Drakon, or House Devine survivors), then there should be no problems.
I know that it might seem like juggling the rules around just to get Imperial Knights into a Heretic Chaos Army, but the book does mention they are out there.
My friends have agreed to let me use them in our games as House Drakon traitors. It should not be a problem for me as I do not attend many 40K tournaments.
I just hope GW make a special updated Chaos Knight miniature (with Chaos Symbols on it), EBook Codex, or release something like Hell Knights, and other Fallen Slaanesh Knight Titans to allow heretics and anti-Imperial generals like myself to field something other than the expensive 888 point Super heavy tank with a Chaos warrior on the front, that is not worth the points it costs.
I am not saying the Imperial Knight is worth its points. I have killed one myself with Abaddon in close combat, as well as a Wraith Knight in another game with him. I have also seen a Wraith Knight take out an imperial Knight.
I have been using an Imperial Armour Storm Eagle to transport him and his squad, then deploy him into close combat after I disembark from the assault ramps.
I know there are a few rule sticklers out there who will not let another player use Imperial Knights with Chaos Marines that are allied to Imperial Guard (traitor), but most would be willing to allow them to be used if painted as House Devine or Drakon.
Are the rules set so strict that you can not do this in an army, or is there some loophole, are the rules easily misinterpreted or is there something you can argue your point with to be able to use Guard - primary detachment, Imperial Knights, and an allied detachment of Chaos Marines?
It might seem like I am grasping at straws, but I am trying to build a themed army list with recently fallen Imperial Guard, the Chaos forces coming to help them resist the yoke of the Imperium - they being the Chaos Marines who are backed up by fallen Imperial Knights - House Drakon.