The Ragefire Chasm is an instance of Orgrimmar in the Orc Capital. The instance has a minimum level of 10, but a level range of 13-18 is recommended to get through without much effort.
Orgrimmar and Stormwind are the two capitals and both have a dungeon. One is the dungeon in Stormwind and the Ragefire Chasm is in Orgrimmar. These two are probably the easiest instances to get to. The instance is hidden in a small corner in the cave area of the Cleft of Shadows. The dungeon is designed for Horde members only, but theoretically it is possible to enter the dungeon as an Alliance player. It won't be worth it if you do, because there are only Horde quests for the dungeon.
The many volcanic caves that make up the Ragefire Chasm run under Orgrimmar, the capital of the Orcs. A mysterious cult is said to have settled in the depths of the Maw. This cult calls itself Searing Blade and represents a danger to Durotar and her independence. Durotar is an area of dusty wasteland in the east of Kalimdor. The area was named after the father of Thrall. The cult belongs to the Shadow Council and this is an evil gathering and it is responsible for many bad deeds. It was led by none other than Gul'dan. He, was one, if not the most powerful, orc witch master. The conflict with the orcs and the Shadow Council has been dragging on for a long time. He even experienced the second war and much more.
The Searing Blade sees itself as the next group of Warlocks to replace the Shadow Council.
The bosses in the Ragefire Chasm are: Oggleflint, Taragaman the Hungerer, Jergosh the Invoker and Bazzalan. The chief and first boss in the instance Ragefire Chasm is Oggleflint. He is the chief of the Flamemouth Troughs and they are considered a danger to the Horde.
Taragaman the Hungerer the second boss and a devil's watch in the Ragefire Chasm. It is believed that he is the leader of the cult of the Burning Blade. The demon can only be controlled by the strongest warlocks and those who are skilled in the demonic arts. He is a Devil's Watch and unlike other demons they fight with their pure power and rely on them to destroy their enemies.
Jergosh the Invoker is the third boss in this instance. He is an orc witch master and is the second leader after Bazzalan. Jergosh has turned away from the Horde to fake being the leader of the burning blade ones and to delve into the demonic arts of the warlocks.
Bazzalan is the last boss in this dungeon. He is one of the leaders of the Searing Blade and together with Jergosh he leads the cult of the Burning Blade. Exact targets are not yet known, but it is suspected that he is planning terror attacks.