Restart your Hearthstone client, because a new adventure awaits.
The magus Medivh is hosting a party in the tower of Karazhan, and in order to attend the shindig, you'll have to meet up with Medivh in the free Prologue mission. He'll even hand you two copies of Enchanted Raven and Firelands Portal just for stopping by, so take the trouble to say hello to your host.
The new adventure contains four wings: The Opera, Karazhan: The Parlor, The Menagerie, and The Spire. It also includes nine Class challenges and 43 new cards.
At present, The Opera, Menagerie and Spire have yet to be revealed to players.
Those who purchase the entire One Night in Karazhan adventure within the first week of release will have the Karazhan Nights cardback added to their collection.
Hearthstone: One Night in Karazhan will run you £14/$19.99 on Android, Mac and PC or £15 on iOS. Wings can be purchased individually or in bundles.