This is the official cinematic trailer for World of Warcraft's second expansion, Wrath of the Lich King. The original description for the content featured in this expansion is below. The full overview can be found here: http://battle.net/wow/en/game/patch-notes/3-0
You've mastered the challenges of Outland, but are you ready for what's yet to come? From the frozen north come tidings of a dormant evil awakening, filling the hearts and minds of Azeroth's citizens with unease. Heroes across the land are preparing for the harsh journey ahead with a sense of anticipation and purpose. Echoes of Doom, the last major content patch for World of Warcraft: The Burning Crusade, lays the groundwork for the upcoming Wrath of the Lich King expansion. It adds a wealth of improvements and entirely new gameplay features to World of Warcraft.