Wizards of the Coast has unveiled Mystery Booster Commander, a new spin-off set announced at MagicCon Amsterdam on 17 July that adapts the popular but hard-to-find Mystery Booster format specifically for Magic: The Gathering's Commander mode. Each pack will contain 20 cards, mixing legendary reprints with 59 cards designed exclusively for the set, and it introduces a new mechanic called Rulebreaker that lets players bend one of Commander's usual deck-building rules.

Two cards were shown off at the announcement: Joven and Chandler, a nostalgic legendary red creature referencing the 1995 Homelands set, and Tolabow, Loch Rascal, a legendary blue otter demonstrating the Rulebreaker mechanic by letting players include a second colour's instants and sorceries in their deck. Eight cards in total will carry Rulebreaker abilities, developed in collaboration with the Commander Format Panel. Mystery Booster Commander will launch at GenCon in Indiana, which begins on 30 July.