Thanks for discussing card power. Often, new players buy too expensive cards because they think the cards are needed to win more matches. I recommend buying the least expensive gold cards. This gives power and more DEC on wins. If you decide to invest in a more expensive card, consider a good summoner like Mylor Crowling. The thorns feature will help you win many lower level matches and boost your ranking. (edit) Just checked your history and saw that you already bought a good summoner

Also, good luck on the Earth splinter this season. Here's some encouragement in your account until the end of season