20 red vampires on level 2 are more effective than just destroying buildings...
These vampires simply create N skeletons! where 200<n<1000 (let's be modest) )))
and the main hero can handle the rest of the army while the other two clear the entire map... so...
I remember when SoY was the only expansion, you could upgrade units, it was fun, but against a strong player, it was impossible to win...
although back then you could also annex (but without diplomacy)...))