private void addDoubleFace(List<Card> booster) {
for (int i = 0; i < numBoosterDoubleFaced; i++) {
CardCriteria criteria = new CardCriteria();
criteria.setCodes(this.code).doubleFaced(true);
if (rnd.nextInt(15) < 10) {
criteria.rarities(Rarity.COMMON);
} else if (rnd.nextInt(5) < 4) {
criteria.rarities(Rarity.UNCOMMON);
} else if (rnd.nextInt(8) < 7) {
criteria.rarities(Rarity.RARE);
} else {