Interesting, when I played with Pyromancer, the popping-up Guardian Skulls did consume all generated souls.
After I created Daemon Warrior, souls keep still adding up (hundreds later in the game), and also Guardian Skulls still are summoned.
Is it because as Warrior I cannot cast spells? Or just a coincidance?
Anyways, despite it is in most scenarios sufficient, to have unpenetrable base defense (sometimes with multiple remote bases), Warrior is not really the class to go for.
I was hoping that all the produced units will be set to guard hero, so the hero can roam the map, steal or destroy mines, with some luck hunt down weaker enemy heroes etc.
But despite my Warrior has nearly 600 HP, and high DEF/RES, still can die (two times due the violet poison, that can actually kill ya). I hoped that the help, with 1% chance of Archon (Cure spell) would be a good strategy, still two times I lost my hero despite high precautions. Without hero, I could lost the chance to create the cool towers and I had to resign, as the enemy could not destroy my base, and I could not destroy his.
What is surprising, is that my buffed hero failed to kill enemy hero, so battling enemy who still has living hero required more assault power, not only defensive power.
Support or summoner heroes seems to be more of a fitting combo with The Iron Fortress, they can sit safely in one of the many well defended towers and summon fire elementals or Pit Friends or just give bonuses to income or army...
I quickly tested Tinker, who was lacking the casting power (no Ritual skill and low INT), but still was able to get Acquire spell to 100%, so he magically turned into the best mine thief evaaaa. Giving infinite resources (all apart Gold) and Tactician boosting the army around.