World Championship in Heroes of Might and Magic III.

Playing as Swamp, I often found myself getting blocked specifically on the 8mm attack. Perhaps it's subjective. The attack power on level 1 heavily depends on luck and resources. That castle, where you get restarts, is mainly about the strength of the starting army, which isn't particularly interesting for Might & Magic VI.

P.S.
Valentine)). I hope you're not serious.