Flip Cards
The Champions of Kamigawa set contains ten "heroes" that are easily recognizable by their unique card frame:
You ignore the information on the bottom half of the card until the creature in play "flips" when certain heroic conditions are met. When you flip a hero, you turn it upside down and play with the other half of the card. All of the flipped versions are legendary creatures and have powerful abilities.
The official rules for flip cards are as follows:
508. Flip Cards
508.1. Flip cards, such as the "heroes" from the Champions of Kamigawa set, 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: The Gathering_® card back.
508.1a 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.
508.1b 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 in play and only if the permanent has been flipped.
508.1c A flip card's color, mana cost, expansion symbol, illustration credit, and legal text don't change if the permanent has been flipped. Also, any changes to it by external effects will still apply.
508.2. In every zone other than the in-play zone, and also in the in-play zone before the permanent flips, a flip card has only the normal characteristics of the permanent. Once the flip permanent in the in-play zone has been flipped, the normal name, text box, type line, power, and toughness of the flip permanent don't apply and the alternative versions of those characteristics apply instead.
Example: The "heroes" in the Champions of Kamigawa set are flip cards whose alternative versions are legendary but whose base versions are not. An effect that says "search your library for a legendary card" won't find a hero. An effect that says "legendary creatures get +2/+2" affects a hero in play only if the creature has been flipped.
508.3. If you control a flip permanent, you must ensure that it's clear at all times whether the permanent has 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.
508.4. Flipping a permanent is a one-way process. Once a permanent has been flipped, it's impossible to flip the permanent back again. However, if a flipped permanent leaves play, it forgets its previous existence.
* Only the characteristics name, type, subtype, supertype, rules text, abilities, power, and toughness are affected by flipping a permanent. The mana cost and expansion symbol are printed on only one side each but apply to the permanent regardless of whether it has been flipped.
* When you flip a permanent, any counters or other effects remain on it. So if a creature with 1/1 printed on the normal side and 2/3 printed on the flipped side has a +1/+1 counter on it, it changes from a 2/2 to a 3/4.
* Flipping a flip permanent a second time has no effect. To "flip" a permanent means to change it from the top half to the bottom half, not to change it from one side to the other.
* When one of the Champions of Kamigawa flip creatures flips, it becomes legendary. If another legendary permanent with the same name is in play, all of them will be put into their owners' graveyards.
* If you're asked to name a card, you can name either side of a flip card. However, the card only has its normal name unless it's in play and has flipped.
* If you copy a flipped permanent, you get the normal, unflipped version. That copy may flip later if certain conditions are met.
* We recommend that you use some kind of marker (such as bead, coin, or card sleeve) to identify whether or not a flip card has flipped.