Heroes with high attack and defense values dominate the original game.
Try to play academy with Light magic against Haven or Stronghold.
Early game (month 1) things are ok for both sides but as soon as the Haven hero gets high defense or attack he goes through creatures on the map like butter. Same goes for enemy heroes with low attack/defense stats.
Not to mention that heroes with no spellpower can use frenzy.
ToTe is full of imbalances in its very core.
here is one for starters - Heroes that pick Magic schools can pick a perk that strengthens a spell which the hero may never get.