From WoWWiki

Instance attunement refers to the process of gaining permanent access to an instance. The term comes from one of the first of such quests created:  [60] Attunement to the Core. Many of the endgame instances require you to complete a quest or obtain a certain item to allow entrance. Listed below are all the instances that require an attunement and how to complete it.

With patch 1.11, players received a keyring which is essentially a permanent bag in which a number of keys can be out into. Unfortunately, not everything is considered a key. The Scepter of Celebras, for example, is not seen as a key and keeps taking up space.

Since patch 2.0.1 the keyring grows dynamically as the player gathered more keys (instead of a certain number slots per so many levels).

• For a detailed look at attunement to the non-Burning Crusade instances, see Instance attunement (Original).
• For a detailed look at attunement to the Burning Crusade instances, see Instance attunement (Burning Crusade).

Contents 1 Instances 1.1 Heroic mode keys 1.2 Raids 2 Other keys

Instances

The instances listed here require a key or attunement to access some or all areas of the instance. In some cases a rogue can use lockpicking in lieu of a key. In most cases only one player needs to open the door for all members of the group to gain access.

• Scarlet Monastery (Armory and Cathedral)
• Blackrock Depths
• Dire Maul (North and West)
• Scholomance
• Stratholme
• Hellfire Citadel - Shattered Halls
• Auchindoun - Shadow Labyrinth
• Tempest Keep - Key to the Arcatraz

Heroic mode keys

As of patch 2.3, to enter the heroic mode version of an Outland instance, you must earn honored reputation status (was revered) with a specific faction related to that instance. Once honored status is obtained, the keys can simply be purchased from that faction's quartermaster. The currently available instances and their respective factions are listed below. Please note that all party members must have a key to enter the instance in heroic mode.

Hellfire Citadel	Honor Hold Thrallmar
Coilfang Reservoir	Cenarion Expedition
Auchindoun	Lower City
Tempest Keep	Sha'tar
Caverns of Time	Keepers of Time
Magister's Terrace	You just need to complete the quest chain that starts from Exarch Larethor on the Isle of Quel'Danas.

Raids

Except for Upper Blackrock Spire, all raid members must be attuned or possess a key to enter the instance.

• Upper Blackrock Spire
• Molten Core
• Onyxia's Lair
• Blackwing Lair
• Naxxramas
• Karazhan Only 1 person needs key for entire as of patch 2.4
• Coilfang Reservoir: Serpentshrine Cavern No attunement required as of patch 2.1.2
• Tempest Keep: The Eye No attunement required as of patch 2.1.2
• Caverns of Time: Battle for Mount Hyjal No attunement required as of patch 2.4
• The Black Temple No attunement required as of patch 2.4

Other keys

• Key to Searing Gorge
• Mallet of Zul'Farrak
• Yeh'kinya's Scroll
• Scepter of Celebras
• The Scarlet Key
• Prison Cell Key
• Workshop Key