Necropolis or Castle (Which one is stronger?)

In terms of strength, the castles are arranged in the opposite order (Castle is the strongest), but the heroes wouldn't be heroes if everything in the game wasn't well-thought-out and balanced. It all depends on many factors. And a player choosing to play as Necropolis is most likely aware of the specifics of playing as Necropolis, and with a correctly chosen tactic (based on the map parameters and other factors), they will win. But if you haven't developed the skill to play with this particular castle, you will certainly be defeated by a strong player.