What I have in mind is a map with two instances. Where part of the map is the Blackrock Mountain with terrain doodads and buildings - the other part is Blackrock Spire and Blackwing Lair inside. Players should be able to enter from the balcony where Nefario is or through the gate->Blackrock Spire->Blackwing Lair. I'm just trying to figure out a way like it feels like the dungeons in WoW, but still without being exact copy of it.
In WoW it's like a mixture of Moria, Mount Doom and Barad-dur (though it's not a citadel just a complex of tunnels.)