- The key to the Shadow Labyrinth in Terokkar drops from Shadow King Ikiss, the last boss in Sethekk Halls.
- To get the key to Shattered Halls in Hellfire Peninsula, travel to the far eastern edge of Shadowmoon Valley. Kill Smith Gorlunk near the foot of the northwestern part of the Black Temple. You'll need to turn in the mold drop plus 4 fel iron bars (2 ore = 1 bar), 3 arcane dusts, and 4 motes of fire at Honor Hold. Get help killing a Fel Reaver, then stick the filled mold inside it.
- You don't need the key to the Arcatraz, but someone in the group must have it to open the door. To get the key, take the quest "Warp Raider Nasaad" at Area 52. This will take you to various spots in Netherstorm, ending in a 2-mannable miniboss. Finally, you'll need the two pieces of the key from the final bosses in Botanica and the Mechanar. Neither of those instances requires a key.
- In order to enter most Heroic Mode dungeons, you'll need to be honored with Honor Hold, Cenarion Expedition, Lower City, the Sha'tar, the Keepers of Time, and the Consortium. Each of the 5-man lvl 70 dungeons will get you to revered (ex. Shattered Halls for Honor Hold).
- You can run a single regular mode Magister's Terrace to become attuned for its heroic mode.
Round 3: 10-man Instances
- There is no attunement for Zul'Aman. You also don't need a key to enter Karazhan. However, someone in the raid must have the key to Karazhan to open the door for everyone else. See below for instructions on how to get this key.
- Summoning Nightbane in Karazhan requires additional background work by one or more raid members. Take "The Mark of Vashj" quest just after defeating the first boss in Heroic Mode Slave Pens. You'll need to run Heroic Mode versions of Sethekk Halls and Shattered Halls before returning to the Slave Pens. You will be given an inventory item you can summon Nightbane with.
Round 4: 25-man Instances
Blizzard has removed the attunement requirements for all 25-man instances.
- To get the key to Karazhan, head to Deadwind Pass next to Darkshire. There's a quest giver at the very south of the zone near the instance entrance. With a friend, the quests should go quickly. You will eventually be sent to collect key fragments, each of which is in a large bottle. When you open a bottle, an elite mob will spawn that drops the fragment.
- For the first part of the key, you'll be sent to the Shadow Labyrinth. The key is to the left of the final boss, Murmur. You can get there by inching along the wall without aggroing the boss. To reach Murmur, you will need to kill all the other bosses.
- Then you'll also need to hit the Steamvaults and Arcatraz in whatever order you like for the second and third parts of the key. The Steamvaults key is just to the right of the first boss, Hydromancer Thespia. It's at the bottom of a watery area, and you don't need to fight her to get there.
- The Arcatraz key is in the room up the glass ramp from the first boss, Zereketh the Unbound. Again, you don't need to fight any bosses to get the key. However, there is one voidwalker that patrols too close for comfort around the key, which is to your right as you enter the room at the top of the ramp.
- There's one last step. After turning in your shards, you'll be told that only Medivd can activate the key. To talk to him, you'll have to complete the final event of the Black Morass in the Caverns of Time. You'll need to complete Hillsbrad Hills there first if you haven't already in order to enter the Black Morass.
Other Old Attunement Questlines
For the old attunements to Magtheridon, Serpentshrine Cavern, and Tempest Keep, see Become Champion of the Naaru.
You can also become the Hand of Adal by doing the attuement for Mount Hyjal. Talk to Soridormi at the Caverns of Time to get the quest, "Vials of Eternity." To finish this, you'll need to kill Lady Vashj in Serpentshrine Cavern and Kaelthas in Tempest Keep.
For the Black Temple attunement Chain, see the page on how to get a Shadow Resistance Neckpiece. It's one and the same. :)