Nice conversions and posing. On the guys with the Achean Pattern helms (2 of them I think?), I'd like to imagine that they were salvaged after chopping off some Sorcerer's head and offering his flaming skull to Khorne. LOL.
That's certainly a great back story idea!
To be honest the helms are 3rd party bitz, from Maxmini. Sadly Maxmini don't exist anymore really and the Steam Knights helms (which these are I think? Or the Scifi Knights ones?
) are not available anymore. Maybe they will come back at some point who knows?
I missed my regular hobby night last night due to real world stuff so no huge progress on the Legion this week. Other projects have also got in the way but hey....hobby's hobby right?! 
The painting desk is still looking hefty:
- 10 man Chaos Squad with bolt pistols & chainswords
- Rhino
- Predator
- Sorcerer
- 5 man Warp Talons squad
- 7 man Chosen Command Squad
- 5 man Terminator Squad
....and as I am a renowned hobby magpie/butterfly I'm sure that I will have more added to that soon! Weathers on the change here so priming wont be an issue any more fingers crossed. Games may even happen later this Summer and it will be great to see some of my new minis in action. The collection is far bigger than when I began 3 years ago and it has a nicer feel to be able to choose what to use rather than make do with what is done.
Long term I am planning a second Havoc unit with heavy bolters, another 2 squads of marines, a 3rd Rhino, another Predator and a Land Raider. Possibly a Defiler to....I'm not sure. I'm not a huge fan of the Daemon Engines in my BL with only Hellbrutes so far.I know that Prot & WarriorFish have success with them in their Black Legion & Renegades armies though....we'll see. 
Happy Hobbying! 
BCC