Avian Gamers Network

Hellfire Citadel
Hellfire Pennisula

Hellfire Ramparts
No requirements.

Blood Furnace
No requirements.

Shattered Halls
Shattered Halls is the 5-man, 70+ dungeon. It is the only way to gain reputation with Honor Hold after you reach Honored, and you need Revered for the Heroic dungeons.

To get into Shattered Halls you need the Shattered Halls Key. To obtain it, you pick up a questline in Shadowmoon Valley. It will end with you back in Hellfire, and you will need to kill one of the Fel Reavers (a 5-man group). You then thrust an item into the Fel Reaver's body, and return it. It will be crafted into the Shattered Halls key. Of course, if someone else in your group has the key, you don't need it, or you can ask people to let you in.

In order to do Heroic dungeons in Hellfire, you need Revered reputation with Honor Hold, and then you'll need to buy the Flamewrought Key. ALL players must have it for Heroic. If four out of five have the key, only four are going in.



Coilfang Reservoir
Zangarmarsh

Slave Pens
No requirements.

Underbog
No requirements.

Steam Vault
No requirements, but this is 70+ dungeon of the instance. No key required to get in, and it's the only way to earn reputation with Cenarion Expedition after Honored. You can pick up a repeatable quest to collect armaments, and killing everything in the dungeon also gives rep (for non-humans, it's usually 12 per normal mob, 24 per bog giant, 125 per boss).

In order to do Heroic dungeons in Zangarmarsh, you need Revered reputation with Cenarion Expedition, and then you'll need to buy the key (I forget what it's called, but I think just Coilfang Key). ALL players must have it for Heroic. If four out of five have the key, only four are going in.



Auchindoun
Terokkar Forest

Mana-Tombs
No requirements.

Auchenai Crypts
No requirements.

Sethekk Halls
No requirements. The final boss of this dungeon drops the Shadow Labs key, which will allow you to get into Shadow Labs (obviously )

Shadow Labs
The 70+ dungeon. You need a key to get in, obtained from the Sethekk Halls final boss. Of course, only one person needs the key, and you can always get someone to open it for you. I think a Rogue with 340 or 350 lockpicking can open the door, too. This is also the only dungeon which gives reputation for the Lower City beyond Honored, which is needed for the Heroic dungeons.



Tempest Keep
Netherstorm

Botanica
70+, requires flying mount.

Mechanaar
70+, requires flying mount.

The Arcatraz
70+, requires flying mount. This dungeon requires a key, which is obtained from the big, white, floating guy in the center of Shattrath. The quest will require you to collect two fragments: one off Warp Splinter (the final boss) in Botanica, and one off the final boss in Mechanaar (I forget his name).


Karazhan/Caverns of Time: Black Morass

To get into Karazhan, it's a fairly long and easy quest chain, up to the very last part. It starts in Deadwind Pass, in Azeroth. You speak to a man, who gives you a quest that takes place 20ft from him. You need to kill some mobs and collect some items. Return them to him. He will send you away to speak to people, and eventually you'll end up back in Outlands.

You'll be required to run through the Steam Vault and Arcatraz to get two fragments of a key. Return to the guy, and he will fashion you the Restored Apprentice Key. When you have this, you will need to go to Tanaris and do the Caverns of Time.

In order to finish, you will need Caverns of Time: Old Hillsbrad, which sees you invading Southshore in an alternate time to complete an event. You MUST do this, or you can not get into the dungeon required for Karazhan. Once the event is finished, you will get a quest to go into the Caverns of Time: Black Morass. Depending on group makeup, this is the hardest normal dungeon in the game. It requires you to kill 18 mini-bosses, 2 of which are major bosses, 1 of which is "the" boss, the big bad guy. All of this is done under a time limit, and all is constant. If you kill the groups fast, good. If you're DPS isn't good, you're gonna get swamped. If you get swamped, either your party will die, or the event will fail as the "time limit" (it involves defending something that starts at 100% and will fall in health) will expire.

Either way, when you complete the Black Morass, you talk to the person you save, who will convert your key, and upon completion, you'll get The Master's Key, which is your ticket to Karazhan.

And yes, everyone needs the key to get.