Necropolis or Castle (Which one is stronger?)

What don't you like about the Necropolis against Chaos? Vampires and ghosts thrive there... the only exception is Ifrits, but... it's not as bad as it seems. (sorry for the off-topic)

Nature against CHAOS with Black Dragons is scarier than the undead.
Because in Nature, 3 Manticores can take down 2 Black Dragons in a one-on-one fight, and two Manticores will remain alive. And if you add Phoenixes, there will be nothing left of the Black Dragons in a couple of rounds, and then Griffons with Serpent Strike and heroes will deal with the rest. Oh, I got sidetracked! :) :) :)

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Let's start with the fact that Cavaliers are built in the first week, while Black Knights are built in the second week at the earliest (if you're lucky). Cavaliers have a bonus, while Black Knights have more health. And if you take Dragons and Angels, there's no need for comment (Angels rule).

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I can say that the chances are equal, but Vampires can do something that no unit from a human castle can do, in equal proportions!

You're not quite right about the Black Knights. Their attack is approximately 30% higher overall. And with an upgrade, they also have a double strike.
And the strength of the undead lies in the skeletons, especially in their numbers. And among the undead, you can highlight 4 units that are the strongest in their class. 1-Skeleton (due to their numbers), Vampire (lord), Lich (stronger than a Fanatic without an upgrade), Death Knight (only Naga can compete with him). :cool: