So I've been playing the crap out of this game. For free players, you start with one deck, and whenever you level up you get enough gold/credits to get a pack or two for free. Plus a lot of the achievements you can get give you packs. Plus you get gold/credits for more packs if you log in enough days in a row. It's very tactical as you have to position and move your cards based on what your opponent is doing. Basically, I've been having a blast with it for the last couple of months.