The final boss that players will face in the next WOW expansion was just unveiled. Garrosh Hellscream, the warchief of Horde will be the one many guilds and players' ultimate goal in Mists of Pandaria. How does Hellscream turn from warchief to the enemy of the world is still being worked and a lot of things, including detailed story are subjected to change. But we know that players will fight Hellscream in the raid called the siege of Orgrimmar - probably Horde and Alliance will have different feeling on this.
In many players' eyes, Garrosh Hellscream isn't an ideal leader but a warmonger compared to Thrall, and it turns out in Mists of Pandaria that he's not a good leader. So is Thrall going to return? Many players want to see that but Blizzard hasn't decided yet.
Although the showdown with Hellscream will set in Orgrimmar, a place that will thrill many players, the process isn't that interesting and innovative. According to Blizzard's current plan, they tend to make Orgrimmar raid a traditional one where you can take down several other bosses and get some loot before you battle Hellscream.
Garrosh - quest giver, chieftain of Warsong, warchief of Horde, and big villain (in the future)
The oriental style Mists of Pandaria expansion will release later this year and Blizzard just revealed lots of information about the 4th expansion. Check out wow.mmosite.com to learn more.