One Night in Karazhan
August 12, 2016
One Night in Karazhan is the fourth and the latest Hearthstone Adventure. It was announced on July 29th 2016 and the free prologue mission went live on August 12th 2016. 
Similarly to previous Hearthstone Adventures players have to undertake series of single player missions in games that feature creatures of Karazhan, custom rules and new cards. Completing a wing rewards players with a Legendary card and unlocks class challenges.
In One Night in Karazhan players have four wings of three challenges to complete in addition to the free prologue mission.
Players who defeat all bosses in The Parlor earn two copies of Cloaked Huntress and Arcanosmith and the Legendary card Moroes. It also unlocks Priest and Shaman Class Challenges.
Players who have defeated the Opera wing receive two copies of Swashburglar and a copy of the Legendary card Barnes, they also have access to the Warlock and Paladin Class Challenges.
Players who defeat The Menagerie challenges obtain two copies of Menagerie Magician and the Legendary card The Curator. Defeating this wing also opens Hunter, Mage and Warrior Class Challenges.
Completing The Spire means player has defeated the entire One Night in Karazhan Hearthstone Adventure. Rewards for this are two copies of Violet Illusionist and two Legendary cards, Prince Malchezaar and Medivh, the Guardian. It also unlocks the final two Class Challenges, Rogue and Druid.