24 booster pack per box, 15 cards per booster pack.

Each Mystery Booster: Convention Edition booster box contains 24 packs from the main Mystery Booster set, plus one extra-special “R&D” card. You won’t believe the stuff they came up with!

Mystery Booster: Convention Edition is designed to emulate a Chaos Draft as it contains more cards than any Magic set ever at 1,670 reprinted cards. In addition, each pack contains 1 of 121 different playtest cards that are exclusive to Mystery Booster: Convention Edition.

Please note that the list of possible cards as well as the art from two playtest cards have been altered from the original 2019 release. Find a list of all the changes at the link below:

https://magic.wizards.com/en/articles/archive/news/mystery-booster-convention-edition-returns-store-events-2021-06-21

Each pack contains:

• 2 white commons or uncommons
• 2 blue commons or uncommons
• 2 black commons or uncommons
• 2 red commons or uncommons
• 2 green commons or uncommons
• 1 multicolor common or uncommon
• 1 artifact or land common or uncommon
• 1 rare or mythic rare from before Core Set 2015
• 1 other rare or mythic rare
• 1 special "R&D" card