The strongest castle in Heroes of Might and Magic IV.

So, according to you, Death doesn't have a worthy opponent by definition? That's fundamentally incorrect. Nature is a very strong counter to Death. As is its castle, magic, Necromancy, and Demonology. Vampires are strong, but not all-powerful.
Don't forget that a Nature mage can also become a Demonologist. And if it's an archmage with skills in Nature, Death, and Life!