The very nature of purchasing Power Discs in a blind bag leaves them a big mystery, and that makes them collectible. The common discs have about a 5% chance of appearing in the foil bag while the rare discs only have about a 2% chance of showing up. There are some tricks to try to feel the foil packaging to get an idea of the type of disc you could be getting (circular or hexagonal), but you still can’t guess exactly what is inside. You can find specific Power Discs in a secondhand marketplace, but the best way to collect them is to swap with friends. If you don’t have a community to trade with, look for retail swap events where you can meet new people and try to complete your collection.
Disney Infinity 2014 Revised Edition eGuide Power Discs