All castles in Heroes 3.

Necromancers... even against a Conflux, going with skeletons and tearing them apart...

Well, going on an assault with only skeletons... :D
And besides, there are some good alternatives to Necropolis units in the Conflux.
Phoenix is better than Bone Dragon and Ghost Dragon.
Ice Elemental is better than Ghost.
Air Elemental is better than Zombie (imo!:D)
And magical elementals are still a good alternative to Black Knight.

I usually play as Necromancers. Free skeletons are a bonus.))))