Cho'gall Heroic World First Kill by For The Horde
For The Horde was the first guild in the world to kill Cho'gall in the Bastion of Twilight in Heroic Mode, making them also the first guild to unlock the very scary Lady Sinestra! Congratulations to them!
You can probably expect a few more information on the encounter soon! (Depending on how much they want to keep things secret for a Sinestra first kill)