Ever since BC i have wondered what the Burning Legion wanted in Karazhan, while an actual was never given during Burning Crusade, Patch 7.1 will most likely give an answer.
Speculations ahead.
Prince Malchezaars presence atop Karazhan has been a mystery, his quote mentioning all dimensions rather cryptic...by the time.
Since WoD we know, that the Burning Legion works outside of reality, that there is just one Legion, giving the speculation that the Netherspace was actually in the Twisting Nether some substance, especially if you take into account that Prince Malchezaar is one of the few famous demons that have yet to be seen in Legion.All realities, all dimensions are open to me!
Now here are the interesting part(s).
Archmage Alturus makes quite a comment on Karazhan, in hindsight.
During BC anyone would have put this comment aside for some random trivia, but with the knowledge from WoD and the Legions interest in Karazhan, this comment actually gives a lot to speculate.Archmage Alvareaux once wrote a treatise exploring a fascinating theory. He proposed the existence of an exact copy of Karazhan in a world other than our own and that both somehow shared the same space.
He went mad soon after. A real pity.
About the exact meaning you could probably debate, but it most likely means that Karazhan works outside of time, similiar to the Legion.
This would obviously bring Medivh into question, but Medivh doesn't seem to really work like anyone else in matters of time.
During the Karazhan pre quest, you had to bring your Karazhan Key to Medivh in the Black Morass to receive his enchantment and thereby grant entry into Karazhan.
Instead of enchanting yours, he simply gives you his own, while this not really special, this dialogue from the quest pretty much basically says that Medivh knows what he will do and what will happen.
That key, I recognize it. That is Khadgar's key... of course I haven't given it to him yet.Now the final interesting thing about this is Khadgars comment on you presenting Medivh's key.I seem to have memories about future events surrounding you and this key.
<Medivh looks at you like he's just seen a ghost.>
You have trying times ahead of you, <name>. Let us hope your strength does not fail you.
Regarding the key, I am to hand it to Khadgar when he's sent to me. I couldn't hope for a better apprentice.
I suppose you will need a key of your own.
<Medivh reaches into his robe and hands you his own key.>
http://wow.gamepedia.com/Quest:Return_to_KhadgarHis own key? That's incredible!
I do not sense any disturbances in our timeline, so I suppose it was meant to occur all along.
This was apparently bound to happen all along, bringing Khadgars key to Medivh in the past, nor taking his key with you to the future caused any disturbances in the Timeline, further hinting that, at the very least, that the rules of time do not apply to Medivh as they do to us.
Finally, during the Karazhan quest currently on Live, an Echo of Medivh also makes one comment that might be interesting on this subject:
And to move that answer out of the way as well, the "Master" Moroes spoke of in the Karazhan trailer seems to be Medivh:Echo of Medivh yells: That which was foreseen has come to pass. The circle nears completion. Sentries, attend to our "guests"!
http://wow.gamepedia.com/Quest:Hiding_in_the_StacksThar'zul yells: You can't stop us, mage! Your former master opened the way to our victory! Karazhan will be ours!