By
pigmonkey on 2006/12/14 (Patch 2.0.1)
This is the coffer that is located in the Blackrock Depths instance, and you may have heard of the "coffer runs" which involve specifically going in for this. To get to the room, you may be able to sneak by the crowd at the top of the Arena, unless you have a lower level player with you, in which case you will have to complete the arena challenges. You then make your way up and around, and soon you will find yourself on a ledge with house-type buildings looking down on Lord Incendius. One of the buildings to the right has a back room filled with locked safes and a few stone guard statues.
You may notice there is a Dark Coffer straight ahead, but this cannot be opened until you get the key. To do this, back up into the room before the safe room and look on the left wall. You have to inspect the poster and it will tell you where the guard with the key is in the instance. You must then hunt him down and kill him, which can sometimes be a very long process since his position is random each time you reset the instance. Once you return, all you have to do is open up the Dark Coffer with the key and loot it. Note that there is NOT one quest item drop out of here for the Libram enchants for each person. Only one can loot it.
There is another optional thing to do here, and that is to open the rest of the coffers with the normal Relic Coffer Keys that you find off trash mobs or on the Auction House. The chests have everything from gray trash (which could sell up to 50s apiece) to bags of gems and bags of money. Here is the full list:
http://www.wowhead.com/?object=160836 After you open all 12, Watchman Doomgrip will spawn, and the four stone guardians will come to life. If you successfully kill everyone, a secret latch will open below the Dark Coffer allowing you to open the chest for a rare item. If you are on the quest "The Heart of the Mountain," you complete that here. The drops that the secret safe contains can be located here:
http://www.wowhead.com/?object=161495