"Valar Dohaeris" is High Valyrian, the response phrase to "Valar Morghulis," the title of the Season 2 finale. Commonly used in Braavos, "valar morgulis" means "all men must die" (in the sense of "all men must [eventually] die [sooner or later]"), and "valar dohaeris" means "all men must serve."
Original Game Of Thrones Cup
Game Of Thrones Collectable
VALAR DOHAERIS - ALL MEN MUST DIE
comes complete with official Game Of Thrones Box