Mental Magic

Mental Magic is an unsanctioned variant format in which a card can be played as any card in the game with the same exact mana cost. For example, Scathe Zombies can be used as Unhinge, Stinkweed Imp, Looming Shade, even Yawgmoth's Will. However, once a card has been named by any player, it can not be named again during that game. In addition, any card may be played, face down as a "Utopia," which can produce any color of mana. As the format is unsanctioned and definitively casual, exact rules change from group to group - groups must decide on their own banned lists, on whether Utopias count as "Plains Island Swamp Mountain Forest"s, etc.