Under the frigid expanses of Dragonblight, a dark secret is kept.
Sartharion with his three lieutenants keep vigil over a clutch of
twilight eggs.  The dark future that these eggs could set in
motion could wreck havoc all across Azeroth. To learn how to defeat
Sartharion and about the loot and achievements related to this
instance, look here.

The Obsidian Sanctum
allows for 10 or 25 man versions of the raid, and
also allows groups of raiders to decide if they would like to kill all
three drakes, or leave some combination of them alive. Defeating
Sartharion with one or more drakes up increases the difficulty but in
turn improves the loot drops.

To read all about it click href="http://www.tentonhammer.com/node/76775" target="_blank">here