Hearthstone: Heroes of Warcraft has been out for a couple of years now, and the game has taken on a speed and pace all it's own. While there are decks and builds in which you can adopt a slow, meticulous game, if you're wanting to climb the ladder in ranked play, you're going to need a deck that hits the ground running on turn one and Never. Lets. Up.
Blizzard has been aware of this, and they've tried to incorporate cards which would change the pace of the game. Cards like Loatheb, Emperor Thaurissan, Reno Jackson, and others are best served in slower decks, and the mechanic informally referred to as Joust also seemed to be a way to make games become more of a strategic puzzle and less of a practice of emptying your hand.
Enter the Old Gods, and sure enough, the game takes on a brand new identity.