All castles in Heroes 3.

I was talking about the strength of the faction not when playing against the computer, but when playing against another player! And even on XL difficulty, with two Inferno Castles, there is a need to build portals between them, but it's too expensive because you need two! It's much easier to use simple scouts, building them in a chain, just like with any other Castle. Or find a town portal in the guild. And playing against computers on any difficulty is not interesting.

Added 3 minutes later
In general, all this needs to be tested in a duel. If anyone wants to play, I'm ready to play with any Castle against any, as you wish.