Mystery Booster is a booster pack release inspired by those Chaos, Cube, and off-format drafts or sealed events. It is, in effect, a chaos draft or sealed in a pack. With some twists.
With over 1,800 cards available, each Mystery Booster event will be an unpredictable new experience! We’ve included a wide range of cards from previous sets, from collectible fan favorites to exciting Booster Draft and Sealed all-stars. To celebrate Magic’s history, each card is printed with the Planeswalker symbol in the lower-left corner but is otherwise unchanged from its previous printing.
The set itself contains a whopping 1,694 reprints from all throughout the game’s history (see below for the full list), plus 121 copies of something new and surprising. You could fill an entire eight-person draft and not see the same card twice.
Mystery Booster Revealed – Blake Rasmussen – DailyMTG.com
The Release Notes include information concerning the release of the Mystery Booster set, as well as a collection of clarifications and rulings involving this set’s cards. It’s intended to make playing with the new cards more fun by clearing up the common misconceptions and confusion inevitably caused by new mechanics and interactions. As future sets are released, updates to the Magic rules may cause some of this information to become outdated.