These are my "mutant bi-mech" spawn:
And Bio-mech zombies:

Wow man, inspiring stuff there! Fantastic heldrake as well! I stole my heldrake idea from the internet, and it pales in comparison to your's, but I'm proud of it none the less:
I'm working on a Iron Warriors *count as* Nurgle army, with the whole logic being all that iron within and without making them as tough as Plague Marines.
Man, I gotta know what you used for the Bio Mech Spawn, and what is that thing behind the Zombies? Maulefiend Count as?
As for the Army, I think some gunline armies (
DA and tau) will give you trouble, but those models are too gorgeous not to use. My only other question, why the hades Autocannon on the drake? popping transports / rear armor?