Blizzard has revealed more about the latest addition to Hearthstone in "Ashes Of Outland" with the introduction of the new Demon Hunter class. The new class is the first of its kind, in that it is the first new class to be added to the game since it originally launched. The story behind the character is that Outland had been razed by an unstoppable force for destruction known as the Rusted Legion. These days within the World Of Warcraft universe, the denizens still exist within the realm as scavengers. You as a player in a small story mode will journey to The Black Temple as it stands as the last bastion of civilization. Where you will meet Illidan Stormrage and his army of Demon Hunters. Here's more info on that story thread which you will use to unlock the new class.
"The fearsome Demon Hunter features an in-your-face playstyle—cutting down foes with weapons and claws, or crushing them with enormous Demon minions. Demon Claws, the class's Hero Power, is a one-mana-cost boost to the Demon Hunter's Attack, designed around robust synergies with its class cards. The Demon Hunter hero class is free and can be unlocked now by completing the Demon Hunter prologue campaign consisting of four story-focused single-player missions, which retell Illidan Stormrage's origin story from his perspective in the Hearthstone universe. Unlock the Demon Hunter upon completing the prologue and receive, for free, all 10 Demon Hunter Basic cards, a 20-card Demon Hunter Initiate set (belonging to the Year of the Dragon for rotation purposes), and a pre-built Demon Hunter starting decklist—so long as you have an open deck slot. Starting with Ashes of Outland, 15 new Demon Hunter cards will be released with each future expansion in the Year of the Phoenix."
The new update also came with content beyond the Demon Hunter, as the "Ashes Of Outland" adds a total of 135 fel-infused new cards to the game. You get two new novel mechanics in the form of Primes and Imprisoned Demons which have their own lasting effects on the game once they're put into play. What's more, from now and June 29th, anyone who logs in to Hearthstone will receive the Kael'thas Sunstrider Legendary minion, absolutely free. You can read more about the update and the new cards here.