Foundations is a new type of set designed to carry through multiple Standard rotations. It contains mechanically unique card designs as well as "less-complex, clean and elegant" reprints, functioning similarly to an "evergreen Core set". Unlike other Standard-legal sets, cards in Foundations will remain legal in Standard until 2029, at least. Foundations is intended to be reprinted and released annually over that period.

The set is approximately 50% reprints and 50% new cards (133/136), which are designed to be similarly straightforward. They are aimed to have resonance, flavor, and top-down designs to create maximum understandability for new players. Conceptually, the set is designed to represent "what Magic: The Gathering is" fundamentally and includes key cards from the game's past that are both functionally useful to many decks and archetypes while also being iconic to the game's history and mythos. A big part of the set is a curated play experience designed for newcomers to the game (i.e. the Beginner Box and the Starter Collection), which is the most robust "learn to play" product yet. While the set also contains staple cards targeted at more advanced players, these can only be found in the booster packs. In this way, the products are split into different target audiences.

Foundations contains 292 regular cards (91 commons, 101 uncommons, 60 rares, 20 mythic rares, 20 basic lands), and includes randomly inserted traditional foil versions of all cards. The new cards are #1-133 and #730, and the reprints are #134-271. There are 20 basic land, including 10 full-art "face character" basic lands (#272-291). Alternate card frames have a different number than the original version. Borderless cards are #292-361. Mana Foils are #362-421. Japan Showcase are #422-431, and #432-441 in fracture foil. Extended art cards are #442-489. The Beginner Box reprints are #490-565 and the Starter Collection reprints are #565-727. The promos are #728-729. The new cards Firespitter Whelp, Goblin Surprise, Starlight Snare, Dropkick Bomber, Dawnwing Marshal and Hinterland Sanctifier are out of order as #197, #200, #514, #537, #570 and #730 respectively.