Blizzard doesn't make many games, but when it does, millions of wallets perk up. World of WarCraft still has 9.6 million subscribers shelling out as much as $15 a month, and Diablo III sold 12 million copies in 2012. Now, the company with the most lucrative video game franchises in history may have found a third revenue stream that its fans will adore: virtual collectible cards for a new game called Hearthstone.

This week, Blizzard announced Hearthstone: Heroes of WarCraft at the PAX East gaming convention, and revealed the first details about the game. It's a Windows and Mac OS (and eventually iPad) title that draws a little bit from Magic: The Gathering. You buy packs of five digital cards from an initial set of 300, choose one of nine WarCraft heroes to set the theme of your deck, then duke it out online with friends using "a wide range of colorful Warcraft spells, weapons, and characters."

While many card games like Magic: The Gathering and indeed Blizzard titles like StarCraft II feature lots of strategic complexity, World of WarCraft has a much broader audience that Blizzard seems to be trying to tap here. Early cards shown are comparatively simplistic, and the company says it hopes to make the game easy enough to understand that new players can learn the basics within five minutes.

The game itself will be free-to-play, but packs of cards will cost an undetermined amount (Blizzard suggested roughly $1 each) for five cards of assorted rarity. Polygon reports that Blizzard's working on cross-platform support, hoping to allow Windows, Mac, and iPad gamers to all play together. The company plans to launch a beta test this summer, which you can sign up for at Battle.net, and release the full game later in 2013.