https://www.gamespot.com/articles/new-hearthstone-expansion-kobolds-and-catacombs-re/1100-6455248/

Kobolds & Catacombs, the next expansion for Hearthstone: Heroes of Warcraft, now has a release date--and it's soon. Blizzard announced today that the expansion will arrive on December 7 in North America, with a release for Europe coming a day later.

As announced at BlizzCon, Kobolds & Catacombs comes with 135 new cards, including new card types such as Spellstones and Unidentified items. Also new in the expansion is the Dungeon Runs single-player mode, which Blizzard says contains 48 different encounters. Additionally, everyone gets a random legendary weapon card and three Kobolds & Catacombs card packs for free just for logging in.