"Hearthstone's" completely free "Kobolds and Catacombs" expansion officially launched last Dec. 7. Hearthstone is a free-to-play online collectible card video game by Blizzard that is available on PC, Mac, Android and iOS devices.

Players of this video game are now able to purchase and open "Kobolds and Catacombs" card packs. Upon log-in, a Legendary Weapon card and three free "Kobolds & Catacombs" card packs will be given to the player for free.

The package features 135 new cards, legendary weapons for each character class, and "Dungeon Run," a new single-player "rogue-like" mode, according to its official blog. In Dungeon Run mode, players can kill off random encounters to earn treasures, and upgrade their "Hearthstone" card decks. For those players brave enough to embark and finish this journey for each character class, a "Candle King" card back is rewarded.

Emerging from the tunnels in the bowels of Azeroth, the "Hearthstone" expansion is packed with a lot of fun and special endless adventures, and lots and lots of treasures. It showcases Spellstones, cards containing "stones" with special magical abilities that can be unlocked by a specific key, available for each specific class. Lastly, it offers Unidentified items, or cards possessing mysterious and strange magics that the player can risk having as part of his deck.

According to Mike Morhaime, Blizzard CEO and cofounder, "Kobolds & Catacombs harkens back to the type of old-school fantasy-gaming experience that many of us at Blizzard and in the community grew up on. We think players are going to love the new cards and testing their mettle in Dungeon Runs, and we can't wait to see how deck strategies evolve with the new mechanics we've added with this set." The expansion is now available for download on Windows PC, Mac, Android and iOS devices. Card packs can be bought individually or in bundles, at the same price as any other "Hearthstone" purchases.