Offline tournament for HoMM V – "In Pursuit of Power".

Yes, he's cunning; you can't use the editor. You can fix something there, so don't ask such questions, or you'll be kicked out of the tournament.

If you make some changes, fix something, or add something, it will only change the map itself, but the save will remain the same as it was. However, after the changes, the save might not load because the map has been altered.
Otherwise, all changes made to the map will not be reflected in the save.