Seasoned players of free to play trading card games or players that invest large amount of money in digital or physical trading card games, end up having superfluous cards that hold no value to them. The purpose of this thesis is to create designs that would counter this problem. We analysed a selection of popular games on the market to get a better understanding about the depth of the problem and existing designs and mechanics to counter said problem. With the knowledge gained from the research, we intended design several systems that would give cards a polymorphic value. To validate those designs we decided to conduct qualitative interviews with highly experienced players of the genre. We discovered from our research and interviews that the problem with superfluous cards was larger than we had anticipated, and few games had taken steps to counter the problem. The systems we designed gave cards a polymorphic value, and the designs were proven successful through our validation. Our research and interviews suggest that by implementing polymorphic attributes to cards it could lessen or even remove the problem of superfluous cards, and at the same time increase the sales figures on booster packs. / <p>Jerry Jonsson går speldesign och programmering och Lina Tonegran går speldesign och grafik.</p>