The expansion features a total of eight Missions which take the player through Icecrown Citadel, culminating in a battle with the Lich King himself. Knights of the Frozen Throne is also the first expansion to feature Missions, a new type of free single-player content. The expansion features the introduction of hero cards, an entirely new card type which replace the player's hero and Hero Power, and the Lifesteal mechanic. Set in the frozen wastes of Northrend and the frigid halls of Icecrown Citadel, the expansion sees each of Hearthstone's nine heroes embrace the power of the Undead Scourge, becoming death knights in the service of the mighty Lich King. The expansion released on Augin the Americas region, and Augin the Europe and Asia regions. Knights of the Frozen Throne ( KotFT, KFT) is the sixth expansion to Hearthstone, featuring the tenth new card set with 135 collectible cards and the new Prince Arthas hero. With the arrival of the Year of the Dragon, Knights of the Frozen Throne is now a Wild format card set, which means cards from the Knights of the Frozen Throne will no longer be playable in Standard format matches.