Obsidia

Obsidia is a black dragon that flies over the Vortex Pinnacle. Be very careful around Obsidia - if she detects you she will spit a fireball at you. (~3000 damage)

As of patch 2.4.2 the dragons in Blade’s Edge Mountains will no longer instantly knock you off your flying mount.

She can be called down to fight as part of the Ogri'la series of quests, or at any time by opening Obsidia's Egg at Obsidia's Perch (requires 35 Apexis Shards. When summoned, she lands and attacks the party.

She also appears in the Obsidian Lair in Twilight Highlands as level 85 elite mob. She is also revealed to be the last breeding black dragon, marked for extermination by Alexstrasza herself.

Attacks and abilities

 * Basic Melee: She doesn't hit hard at all. 600 on a tank, 1500 on cloth, but she swings slowly.
 * Hellfire: Stands still, channeling, 400 fire damage a tick.
 * Fire Breath: 500 to tank.
 * Bellowing Roar: AoE fear.

Strategy
A balanced 5 man should have no trouble with this mob, although she seems to have a fair amount of health.

Really, while the fight could generally be unpleasant due to her range of abilities, her damage output is so paltry, generally she can't kill much of anything even if the tank is feared. You can use a warlock or such to tank her, if you have decent healing.

Loot
Obsidia drops a variety of items, usually including a random rare item, and also an Obsidia Scale.