Two headed giant is a special format for prerelease. You and a friend each purchase a prerelease kit and build 2 40 card minimum decks with contents between the kits. Then, face off against other 2 headed giant teams. 3 rounds swiss. Best of 1. 1 The Hobbit play booster pack per round win. Sign in store starting on Saturday, July 25th. See the official format page for additional details. https://magic.wizards.com/en/formats/two-headed-giant
