Hey, I've been lurking on your thread for quite a while, one of the reasons I joined B&C infact, and just wanted to say what an amazing army you've got. They really capture the feel of the Night Lords in all there gory glory.
For your rubric marines do you plan to leave the skulls suspended by the clear rod? I was thinking it would be cool to have the flames on fire with the flames running over the hood to hide the pin join. This will give them a creepier look (not that your guys can get much creepier mind you) and hide a pin on an otherwise flawless idea. The fluff is good to and the flamming skull mightn't fit with it but here's a thought; do they have to be ex-TS rubric marines? Can they just be Night Lords who have been possessed or, for whatever reason, have been made thrall to the sorc and been turned into little more than undead bodyguards? This would maybe allow you to blend the painting in more with your army rather than have to have TS elements still in it.
Just tossing out some ideas. Once again, awesom army with some amazing ideas and conversions. You very nearly got me making Night Lords but I have too many other projects on at the moment