Mirrodin Besieged Booster Pack Phyrexian FactionFor these boosters, Mirrodin Besieged was divided into two halves. Cards with the Mirran watermarks appear only in Mirran boosters, and cards with Phyrexian watermarks appear only in Phyrexian boosters. There's also one basic land in each booster. Foil cards will show up at about the same frequency as they do in regular boosters and don't follow the rules about what booster they can show up in (both Mirran and Phyrexian foils can show up in either