Number of Cards: 35 cards and 1 reference card Number of Versions: Varies (Throne of Eldraine has 5, one of each color) Contents:
1.1 rares/mythic rares
1 reference card
Nine out of ten Theme Boosters will have one rare, but one out of ten will have two rares. That's what "1.1 rares" means. The number of commons and uncommons in theme boosters varies between boosters, unlike Draft Boosters where the number of each rarity mostly remains constant. You'll always get more commons than uncommons, however. The reference card is new-player information on a card to help expose newer players to different aspects of the game.