C'est de l anglish désolé ^^
KARAZHAN (10-man raid) (Deadwind Pass): Everyone in the group is required to have The Master's Key in order to enter Karazhan. The quest line for it starts right in front of the tower with a woman. She will give you two soloable quests which are done outside of the tower. You must then travel to Dalaran and speak with a mage on the northern side of the city. You will then receive a quest to get the First Key Fragment from a container near Murmur in the Shadow Labyrinth (level 70 Auchindoun wing). Once you complete that quest, you are then instructed to retrieve the Second Key Fragment from The Arcatraz (level 70Tempest Keep wing) and the Third Key Fragment from Steamvault (level 70 Colfang Reservoir wing). After you collect all three fragments you must complete the Opening the Dark Portal (Escape from Durnholde must be completed first in order to be able to enter the Opening the Dark Portal) inside the Caverns of Time to have Medivh complete the key.
"http://www.wowwiki.com/The_Master's_Key"
Other information can t be found here
http://www.wowwiki.com/Instance_Attunement
and here
http://www.worldofraids.com/forum/viewtopic.php?t=2747
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