Hearthstone is one of the most addictive games that I never got addicted to. There was a period of about 3 weeks where I would play regularly, and my friend and I were competing to climb the ranks and build superior decks. It quickly became apparent to me that in order to compete seriously, you have to drop some real-world dough on card packs. My friend was more than willing to do this, investing a questionable sum of money on Curse of Naxxramas card packs, but I realized that with my highly addictive personality I could easily bankrupt my wife and myself. I gracefully bowed out.
Since I left, Hearthstone has seen multiple expansions, and many new cards have been added. This tends to happen with competitive trading card games, and when the deck pool becomes overbearing “rotation” occurs, removing older cards from sanctioned play and pushing players to create new decks and strategies. For Hearthstone, the first rotation is occurring a little earlier than it does with most card games in an attempt to limit the standard pool to around 600 cards and remain inviting for new players. Cards from Naxx and Goblins vs Gnomes will no longer be usable in standard play, but Blizzard is introducing “wild” game modes where cards from all decks can be used. In order to accommodate the decks players will want to build for standard and wild modes, the number of deck slots has been doubled from 9 to 18.
Source: The Guardian