ZFR: Done!
Ironically, after I gave up trying to get 3 stars and just wanted to finish the mission, I managed to kill the 2 cerebri farily easily and then towards the end... lost 5 lives to silly things which I could have avoided easily.
The final boss wasn't that tough as bosses go. The trick was to keep him occupied in strategic positions (purple mage towers + tesla towers) as long as possible with the hero and/or reinforcements (I used the demon samurai one). Also if you build sharpshooters on the upper side passages then they can have the upper middle passage where the boss comes in range and their one-shot-one-kill can be useful.
The final legions had me worried a moment but I got meteor shower just in time.
15 lives left 2 stars. All others 3 stars. All finished on Normal. The first 5 campaign levels were also done in Heroic and Iron.
I'm leaving this for now because if I play one more day I'll be seeing the stuff in my sleep. It was fun, but lots of micromanagement required and some levels were brutal. If I'm feeling bored, or masochistic, some day I might try to get that one missing star from last level and maybe complete the Heroic and Iron. Perhaps even *gulp* Hard difficulty.
Thanks all who helped here, and a big thank you to Slaugh for getting me the game.
Hey well, you're actually a lot further than me, then! I think I only have 85 stars or so. Plenty of levels are not 3-star, and the 2nd-to-last level I've only beaten with 1 life left, ha ha!
I've started it up again because of this thread. We'll see if I can get any further.