To earn the card back, you must reach rank 20 in ranked play before the end of the month. If you're an inexperienced Hearthstone player, we would advise waiting a few days before giving it a shot. A new season of ranked play means a ranking reset. Much more experienced players will be aggressively working their way up the ranks to their usual place and are apt to stomp you if you get in their way up the ladder.
Filed under: Hearthstone Insider