Blizzard's ridiculously popular card-based arena battle game Hearthstone is getting a new expansion, and you'll be able to pre-order it in just a few weeks. Blackrock Mountain will take players deep underground to the Molten Core where powerful creatures await your arrival. Braving the inferno will grant you 31 new cards that can only be obtained in this $25 expansion.

Hearthstone is mostly an online PvP game, but the single-player adventure mechanic is excellent too. There's currently one available in the game, called Curse of Naxxramas. Blackrock Mountain will be set up in a very similar way. The adventure will consist of five wings, each with several boss battles. Beating each one unlocks a few more cards until you've completed the campaign and gotten all the goodies. Some of these cards look really awesome too. I need to get me that Grim Patron.

Pre-orders will be live on March 19th, and the first wing will open up sometime in April. Each subsequent wing will open after one week until all five are available. The entire adventure can be purchased for $25 or you can buy individual wings for $6.99/700 gold. If you pre-order the adventure later this month (cash only), you'll get a unique card back for your collection. I guess people care about that.