Blackwing Descent

Blackwing Descent is an entry-level level 85 raid instance. Having retreated further into Blackrock Mountain following his defeat in Blackwing Lair, Nefarian has been bolstering his forces here and must be stopped once more. The entrance to the instance is near Nefarian's throne in the uninstanced portion of Blackwing Lair and is accessible by flying mount only.

Blackwing Descent, along with Bastion of Twilight and Throne of the Four Winds, is one of the first raid instances in World of Warcraft: Cataclysm and its place in the expansion is intended to be akin to that of Naxxramas in Wrath of the Lich King.

History
Blackwing Descent is a part of the Blackrock Spire complex currently occupied by the Black dragonflight, having been taken over from the Dark Iron dwarves who inhabit Blackrock Depths. However, despite the previous rivalry between the two factions, the alliance between Deathwing and Ragnaros in Mount Hyjal and the presence of Dark Iron golems may suggest the forces of Blackrock Mountain may be fighting together.

The area appears to be a massive laboratory complex, in which adventurers must fight Nefarian's horrific experiments, expanding on the themes previously seen in Blackwing Lair.

Geography
The instance consists of two subzones, the Broken Hall and the Vault of the Shadowflame. When you enter the instance, the Omnotron Defense System will be off to your right with Magmaw off to your left. There is no required order, but Magmaw is usually considered the "first" boss. You next descend into the Vault, where Nefarian's experiments take place.

The Vault branches off into three areas where Chimaeron, Atramedes and Maloriak can be found. Only after defeating all of them will Nefarian himself become available, standing in the middle of the Vault as Lord Victor Nefarius.

Dungeon denizens

 * Black wyrm (two, Nefarian and Onyxia)
 * Black drakes
 * Dark Iron dwarf ghosts
 * Dragonman
 * Drakeadons
 * Drakonids
 * Dwarven golems
 * Gnome (one, Finkle Einhorn)
 * Human (one, Lord Victor Nefarius)
 * Hydra (one, Chimaeron)
 * Lava worm (one, Magmaw)