Split card

Split cards are Magic cards with two card faces. A split card is literally "split" into two seperate cards each with its own card name, art, mana cost, text etc. In any zone except the stack, a split card has two sets of characteristics; while it's on the stack, it only has the characteristics of the half being played.

They were introduced in the Invasion block, where each side was from a different color. In Dissension they were seen again, and each half was a multicolored card from a different guild; finally Planar Chaos introduced the first split cars where both sides were the same color (all split cards in PC were red).