Of Orgrimmar is a title awarded to Horde players upon completing the achievement 
Exalted Champion of Orgrimmar, which requires the player attain exalted status with Orgrimmar and earn the right to represent Orgrimmar in the Argent Tournament.
Orc characters can obtain this title by completing 
[80] The Valiant's Challenge (Horde). Characters of other Horde races must complete their version of The Valiant's Challenge, then complete [80] A Valiant of Orgrimmar.
Patch Changes
Patch 3.1.0 (2009-04-14): Title added.
