What would you change in Heroes of Might and Magic IV?

Regarding the fourth installment: it would be great to have a few super-units, but not to create imbalance, rather to add variety. Make them neutral and give them, say, 1000 HP, then you could create very interesting scenarios and campaigns involving them. And how about gathering a huge army to defeat one incredibly powerful monster! It would be great, perhaps not for multiplayer, but for single-player scenarios.