I've destroyed all the other heroes (highest levels), except one, the daemon hero. I can't kill him. He can call down fire and it takes hundreds of points off me in each instance. There seems to be no limit to how many times he can do this. Also, I made a red wizard and tried to use his ability to shield from fire, it didn't work. Maybe that only works against dragon fire. Anyway, my hero has 6040 hitpoints. My strength is at 249, dexterity, intelligence, & charisma are all also at 249... but, he keeps killin' me, I reload and try to take him again. It's very annoying. I've went to his camp and destroyed all his buildings, but he's still super strong. Another main problem is that I can't make anymore men. At some point in the game, not certain exactly where, all of my buildings stopped making men. I have five, level 5 keeps, and have captured some enemy buildings, which are supposed to increase my army limit. At any rate, I was under the impression that as soldiers died new one would be produced by their appropriate buildings as long as a specific number were maintained. So, unless I'm mistaken, why is this not happening anymore and why is this guy unstoppable??? Thanks in advance for all constructive answers...

Are you running into the army cap? There's a little counter at the top of the screen that shows current and max unit levels, as "22 / 35". It's the left-most counter, looks like a little shield. Beyond bumping into the cap, I'm not sure.