"Demon Hunters brandish the power of fel, while crushing their opponents with colossal demon allies. They have access to cards with the Outcast keyword, which become more powerful when played from the left or right-most position of your hand—including the turn they’re drawn.
The Demon Hunter is a permanent, full-fledged class that will be supported across all future Hearthstone expansions. The Demon Hunter is completely free for all Hearthstone players after they complete the Demon Hunter Prologue missions that become available on April 2. The prologue retells Illidan Stormrage’s origin story, from his perspective . . . and with a unique Hearthstone twist. Upon completion of the prologue, players will receive, for free, all 10 Demon Hunter Basic cards as well as a 20-card Demon Hunter Initiate set. Starting with Ashes of Outland, 15 new Demon Hunter cards will be released with each future expansion in the Year of the Phoenix"
I used to be a fairly hardcore Hearthstone player and stopped as the game was getting much more grindy in later expansions. With that I do plan on heading back and playing the free single player content to unlock the new Demon Hunter class. I'm not sure the Demon Hunter will get me back playing the game regularly but it's fun to see Blizzard add something new to a game that's been around the block.