The fallen dragon Deathwing escape from his underground prison and flew across the planet and killing people randomly if they were unlucky. Death from Deathwing did give the player an achievement so it wasn`t always bad. Deathwing could appear in any zone on the planet of Azeroth.
The expansion also saw the arrival of an underwater zone, one of the first zones that the player would encounter. If Vash`jir wasn`t to your liking, dry Mount Hyjal would be the more perfect tonic to quest in.
Adventuring wasn`t done on a new continent, instead the adventuring was split between Eastern Kingdoms and Kalimdor with portals available from the faction home capital to the zones that they wanted.
The expansion saw the arrival of the Goblin for the Horde and Worgen for the Alliance. The Worgen were a werewolf race that could in peaceful times look human but whenever they fought, they would turn into a werewolf. The Goblins had no alternate feature. The old raids of Zul`Aman and Zul`Gurub were removed and replaced with new heroic dungeons. The Zandalari who you would`ve if you`ve played previous been gaining rep for are now the enemy.
Blizzard started creating heroic versions of the old dungeons, one of the first was Deadmines. The updated version of the Deadmines sees Vanessa Van Cleef take over the Defias criminal game after her father is finally killed.
It marked the last time we would see Championing, where you could wear a factions tabard for rep.