These "power cards" include jokers and wild cards, which can be used to replace any other card in a meld. Players can gain a significant advantage over their rivals by learning how to use these prummy slots apkower cards effectively. Using Power Cards Strategically. Keeping a wild card until the right time, for example, can help you finish a challenging meld or interfere with an opponent's strategy by preventing them from accessing important cards. Power cards have the ability to change the outcome of a game, so players must understand their worth & use them as part of their overall strategy.