Lower Karazhan

[Rokku]

Use the backdoor entrance.

[Tricen]

I would if I had a key to karazhan Q_Q

[Boyiee]

The only locked door should be the back door entrance, there is no locked door to nightbane.

There is a couple ways to get there, you can either go up from the opera stage, after you kill that boss a door opens allowing you to go upstairs to the balcony's around it - we used to do this for cash - after going around and up again and around there is an opening to a dark hallway with ghosts. In this room is the back door, which is locked. In this same room is an opening in the back right corner, near the stairs to go up to curator, that walks you out to nightbanes balcony. Then you have to summon him.

You can also get there coming from maiden.. Pretty much the same thing, dark hallway with ghosts and the back door, and a broken rocky staircase up to curator... nightbane has a door in the corner that should always be open.

If there is any doors locked, which there shouldn't be, I would assume its from needing to kill a boss before hand, which I've never known of.

If you can get to Curator, you can get to nightbane.

[Correction]

Nightbane's story seems kind of retrofitted though, not based on any causality of the raid as a whole. Granted, he's optional, and thus doesn't necessarily have to be causal, but still.

Nightbane doesn't 'live' in Kara though, the quest makes it pretty clear that you and the Violet Eye are deliberately reviving him from the ashes of Arcanagos to retrieve the magic essence Medivh used to kill him. As such he doesn't need much more explaining than that, it's just a powerful being Medivh killed and Dalaran would want the magic leftovers that would produce.

As for Illhoof/Prince the only explanation I can come up with is that Medivh from his birth was a pawn for the ambitions of Sargeras, and Karazhan was built as a way to access other planes of existence (remember Medivh's Big Thing was opening a portal to Draenor), so if it exists as a hub between planes it automatically becomes desirable to the Burning Legion (And the blue dragonflight - Netherspite; and the Consortium), so the invasion by Prince is just the first step in that. Illhoof just looks like a minor experiment gone wrong (there's a charred corpse in front of him) by the warlocks in the service of the Legion.

The only bosses I can't personally justify are Opera, Maiden and Chess. I reckon they're just magical traps meant to defend the tower from incursion by mortals (note the 3 mages trapped and enthralled in the library behind Curator), so I guess they don't need rigorous lore to explain their existence.

[Jodwahh]

inb4 meresgi saying WoW is ruined by Kara.