Campaigns of Heroes of Might and Magic I.

I'm talking about the fifth, sixth, and seventh missions.

P.S. And you're great for managing to complete all the campaigns of the first Heroes game, because they are a bit tedious; I've only managed to complete two so far.

I completed it against the lady. The strategy is as follows: You need to gather a GOOD army and go to their island. Defeat everyone and conquer their castles. Then, to prevent the lady from buying too many Phoenixes, capture ALL the mines, build up a larger army, and get ARMAGEDDON. Go to the lady with heroes level 5. Give one of the weakest heroes to four of them and take ARMAGEDDON (the weakest one should go first), use Armageddon, and BOOM, reduce the army, repeat the procedure "n" times. Then, take your army (a dragon is best, as it can withstand ARMAGEDDON) and attack. CAMPAIGN COMPLETED