New Hearthstone expansion: Knights of the Frozen Throne launches on August 10. There are 135 new cards. Unlike "Journey to Un'Goro" expansion, the new expansion has a single-player content. The expansion has different single-player than those in the past, as it comes with a set of free missions, including a prologue, two wings of three boss fights each, and a final battle against the Lich King. Completing the prologue will award you a random Legendary Hero card, while finishing each wing will also get you a card from the expansion. If you finish them all, you'll also obtain a card pack.
A special, one-time pre-order offer is available for the expansion, which allows you to buy 50 card packs for $50. Also you will get a special card back.
Here is how the environment looks:
You can see all the new 135 cards here: https://us.battle.net/hearthstone/en/expansions-adventures/knights-of-the-frozen-throne/cards
Here is a gameplay with the new cards: