The Master's Key

The Master's Key was the key (and attunement) to enter Medivh's tower of Karazhan in Deadwind Pass. It is a reward from the quest Return to Khadgar. In order for your raid to enter Karazhan, only one person needs to possess the key.

The key can be obtained by completing the following questline, which begins with Archmage Alturus just outside Karazhan:

• 1) Archmage Alturus (quest): Lower City; optional talk to NPC, 5 rep with Violet Eye — Arcane Disturbances: Deadwind Pass; standard soloable exploration quest
• 2) Restless Activity: Deadwind Pass; standard soloable kill quest, can be done at the same time as above
• 3) Contact from Dalaran: Dalaran; talk to NPC
• 4) Khadgar (quest): Talk with Khadgar in Shattrath City
• 5) Entry Into Karazhan: First key part to be found in the Shadow Labyrinth, Auchindoun
• 6) The Second and Third Fragments: The second key part is found in The Steamvault and the third key part is found in Arcatraz
• 7) The Master's Touch: Talk with Medivh in the Opening the Dark Portal (Black Morass) instance in Caverns of Time. He'll give you his own key.
• 8) Return to Khadgar: Return to Khadgar

The whole questline rewards 2100 reputation with the Violet Eye.

Some of the quests in this chain have access requirements that may sidetrack a player. These include access into:

• The Arcatraz, either with a key possessed by a party member, or a rogue with 350 lockpicking. (Note that, after a wipe or if a party member is killed and can not be resurrected, you will need the key again to enter the instance.) The key is obtained through a quest chain in Netherstorm. The Arcatraz can only be reached by flying mount or druid flight form.
• Shadow Labyrinth in Auchindoun also requires that a party member have a key, or you have a rogue with 350 lockpicking. The key is in an easy-to-miss chest behind the last boss in Sethekk Halls, also in Auchindoun.
• The Caverns of Time in Tanaris. This requires everyone in your party to have successfully completed Escape from Durnholde Keep in Old Hillsbrad Foothills. Note: Escape from Durnholde Keep is part of a quest chain that starts with To The Master's Lair, which you obtain from Andormu outside of the Caverns of Time itself.