Problems with Heroes of Might and Magic IV.

A hero always needs an army. Neutral armies grow, and it's difficult to defeat a level 4 creature alone (including Utopias), and there's no point in talking about fighting another player... Level 20 is not that high.

Against another player, there's no argument. But against the AI, their heroes rarely reach level 5. If you equip a level 20 hero with good artifacts, they can defeat even a level 4 creature. I had a level 15 rogue defeat a Dragon King one-on-one.