Hi, I'll show you how to get into Karazhan, without having the key needed to enter. In 2.4, attunement was removed, but you would still need the key to enter karazhan.
You're bored. You've nothing to do. Then you see some in trade, LFM Kara achi run. When you finally get there and all are summoned, you realize that you can't enter, because nobody got the key. OH NOES - chain leave inc.
BUT NO!
[ame="http://www.youtube.com/watch?v=bw75xuRDqTE"]YouTube- Karazhan without key[/ame]
Sorry for bad quality