Balance in the online game on a random map.

https://h3hota.com/ru/rules - here you can find a list of templates (and their rules), choose one that suits your taste. Personally, I like the Mini-Nostalgia template the most - it has a clear structure, it's not too rich, but not too poor either, and the presence of computer opponents adds extra interest and forces you to plan the game much more deeply (not only based on what you see on the map, but also by correctly choosing the factions of neighboring castles, reacting to the opponent's choices). The balance is generally present, although in Heroes it is not optimal by default. But such situations, as you described, occur very rarely.