710.1 Flip cards have a two-part card frame on a single card. The text that appears right side up on the card defines the card’s normal characteristics. Additional alternative characteristics appear upside down on the card. The back of a flip card is the normal Magic card back.
710.1a The top half of a flip card contains the card’s normal name, text box, type line, power, and toughness. The text box usually contains an ability that causes the permanent to “flip” if certain conditions are met.
710.1b The bottom half of a flip card contains an alternative name, text box, type line, power, and toughness. These characteristics are used only if the permanent is on the battlefield and only if the permanent is flipped.
710.2 In every zone other than the battlefield, and also on the battlefield before the permanent flips, a flip card has only the normal characteristics of the card. Once a permanent is flipped, its normal name, text box, type line, power, and toughness don’t apply and the alternative versions of those characteristics apply instead.
710.3 You must ensure that it’s clear at all times whether a permanent you control is flipped or not, both when it’s untapped and when it’s tapped. Common methods for distinguishing between flipped and unflipped permanents include using coins or dice to mark flipped objects.
710.4 Flipping a permanent is a one-way process. Once a permanent is flipped, it’s impossible for it to become unflipped. However, if a flipped permanent leaves the battlefield, it retains no memory of its status. See rule 110.5.