Amani Catacombs
The Amani Catacombs are a series of mummy-infested forest troll crypts in the Ghostlands, located northeast of Tranquillien Village in the mountains. To get there, you should first obtain the quests 
[17] Investigate the Amani Catacombs and [17] Troll Juju. Then, head out of Tranquillien and take the first fork right in the road. If you look on your map, there should be a light blue area in the mountains close to your current location. Head up this path, through some Shadowpine Oracles and into the crypt. You should at least be level 16 - 18 when entering this area, as there are several mobs roaming inside the catacombs of this level.
The Amani Catacombs are also home to many rogue quests, including The Sad Truth. Most of these quests require the rogue to pick locks on the scattered chests in the area to find, among other things, a shrunken head.
