Right now, it's essentially one of the most balanced mods for Heroes 5.5. Despite the fact that it has many new skills and new heroes. Nevertheless, the author even nerfed the Imps; they drain less mana, and he has thought through many things.
I got the impression that you don't understand balance.
I looked at this 5.5 version. There are many interesting innovations, but also many controversial ones, controversial hero classes. Why remove unique castle abilities from heroes in favor of questionable skills? Orcs with magic, when they can't learn magic in the castle? Every level-up offers the opportunity to learn Logistics for any hero. Why would an Inferno hero need Necromancy? And so on. Plus, the game crashes from time to time. It would probably be interesting to play this mod on scenario maps, but not for Multiplayer.
When I said that I could change something in this mod that I didn't like, instead of that, you asked me to create new, unbalanced/fun mods...
Imps are quite unpleasant creatures with 13 initiative (with artifacts, you can get more than 15), they can drain a lot of mana (or even all of it) at the very beginning of the battle, before you can do anything with them. This is especially unpleasant for factions that cannot replenish mana during the battle or have a small amount of mana knowledge. There are indeed some strange changes, but the Imps are fine