Super Unit in Heroes 5.

They definitely exceed expectations, and what about the fact that they are reborn?!!!

They are reborn, and so what? Consider it as having up to 300 hit points, which is within the normal range considering their other characteristics. Remember the Lava Dragon – it has 20 fewer hit points, but its damage is only 10 more. The other stats are generally similar, but the Lava Dragon has more defense and is an elemental, which in itself provides a significant bonus!

Added 3 minutes later

If you don't like super units in this role, you can make them only for neutral creatures, so they can't be recruited into an army. Why? For example, they could guard some great treasures on the map. ;)

An average unit can join a player with a decent army or under the influence of diplomacy. Another argument is that anyone can adjust it in the map editor so that a creature joins them regardless of their army or diplomacy – that's what you call a shoddy job!