Commander Masters Draft Boosters contain:

• 11 Commons
  • In every sixth booster, one common is replaced with the Prismatic Piper.
• 3 Nonlegendary uncommons
• 2 Legendary uncommons
• 1 Legendary rare or mythic rare
• 1 Nonlegendary rare or mythic rare
• 1 Nonlegendary uncommon (in two thirds of boosters) or nonlegendary rare or mythic rare (in one third of boosters)

In a Commander Masters Draft Booster, a traditional foil legendary rare or mythic rare drops at about the same frequency as a traditional foil nonlegendary rare or mythic rare. Non-foil legendary rares and mythic rares are about 15% less rare than their nonlegendary counterparts.