Orcs – Garuna
Demons – Nibrosu needs a different ability; +1 to luck is pointless.
Necromancers – Ravenna
Elves – Talanar (although he can be used for troop gathering, making him a secondary hero, but even that seems insufficient to me. Perhaps giving him the role of treasurer would be better).
Dwarves – Sveya is questionable.
Towers – Irbet (the bonus to the ritual at the beginning of the game is too small, and in the middle and end, with proper development, there won't be any mana problems. Also, the presence of dark magic is confusing, as it's not found in the guild).
Mages – Nura (it's unclear why a mage would need to restore mana in battle, given their knowledge), Faiz (everything is clear here).