This offers huge possibilities, especially on large maps with many external dwellings.

What are the advantages of the original "Heroes of Might and Magic V" over the expansions? Or do the expansions not have the maps that were in the original? Or are there downloaded maps from websites that can only be played on the original version of the game? I haven't played the original game for a very long time (since the release of the first expansion) and I don't understand what the original has that the expansions don't.
P.S. Or maybe "Necromancy"?