This is usually done through test or trial play sessions, during which the deck's performance is evaluated.
The reasons may include: lower cost, better synergy with existing cards, more flexible alternate uses, or increased effectiveness against known opponent strategies.
In addition to manually poring over card text, the Internet has also become a popular source for those seeking deck optimization information.
Players can either directly consult existing deck lists for inspiration, or can ask on online forums for advice or recommendations.
This can drive up the cost of the overall gaming experience, and can in some cases initiate an arms race in local circles, where other players must in turn purchase cards to continue to compete.