The idea of the Mystery Booster product line is that you don't know what it is until you open it up; the mystery is a feature of the product. The main set contains 1451 cards of equal rarity. However, 40 cards have the mythic rare colored expansion symbol, 84 rare, 794 uncommon, and 533 common. The reprints are from throughout the game's history. There are also cards from supplemental sets. Almost all sets from Mirage going forward, including even the smallest supplemental products, are represented. An overlap with the first Mystery Booster was mostly avoided. In contrast to regular Chaos limited, which has many set-based synergy cards that don't work in that environment, this curated set maintains the chaos feel but it lets decks be functional, good, and fun to play. It is described as a "wacky experience".

Like the 2019 Mystery Booster set, most cards in Mystery Booster 2 are straight "pick-ups" that use the original card files. However, some versions are regular reprints with updated oracle text, their own expansion symbol (a question mark), and expansion code (MB2). These have gimmick card frames, i.e. white borders and the Future Sight card frame. Additionally, a few cards are reprinted from digital-only sets and thus mark the first instance of their set symbol, art, and/or the card itself appearing in paper (see Notable cards). About 4.5% of the packs feature a foil card.

White-bordered cards are MB2 #1-121, and the futureshifted cards are #122-265. Some of the latter can appear exclusively in non-foil (#122-144), some in both non-foil and foil (#145-242) and some appear exclusively in foil (#243-265).

Mystery Booster 2 play boosters contain 15 cards.

• 10 Commons or uncommons
• 2 cards of each color
• 1 Multicolored card or artifact of any rarity, or common or uncommon land
• 1 Rare or mythic rare
• 1 Future Sight frame card
• There is a 60% chance for a rare or mythic rare.
• Less than 5% of Future Sight frame cards appear in traditional foil.
• In less than 1% of boosters, this slot is replaced with a traditional foil acorn Alchemy card.
• 1 White-bordered card
• There is a 40% chance for a rare or mythic rare.
• 1 Test card