Or you could save your credits and buy the 50 credit full deck pack, which is the best value of all the packs. I've gotten more rares from those packs than I have the 3 card packs. Granted the odds are better since there's 8 as opposed to 3. However you can always sell your unwanted cards (as long as you have 8 left, for clintz).
The Urban Rivals team is made by lovers of all kind of Collectibles Cards Games and Trading Cards Games like: Magic the Gathering, Dominion, Vampire, Yu-Gi-Oh!, Pokemon, Wakfu TCG, Assassin Creed Recollection, Shadow Era, Kard Kombat and Might & Magic Duel of Champions.