The hero units you hire for your empire have way to low hp.

If you have a monster with 10 dmg in true dmg they die instantly.

The hp should get more automatically per lvl so that they can live through the fight.

I played the game Master of Magic and there you were able to kill even the strongest monsters with them. Here you have no chance to tank a strong monster because if the monster has 130, 250 or 450 dmg NO hero you have has any chance to live through the fight because if it hits you, you are dead. Because even the best armor i got up to now has only 40 armor.