Pain // Suffering

Split cards have two card faces on a single card. The characteristics of the half you didn't cast are ignored while the spell is on the stack.

To cast a split card, choose one of its halves to cast. There's no way to cast both halves of this split card.

A split card's characteristics are a combination of its two halves while it is not on the stack. For example, Assault // Battery has a mana value of 5 while it is in your library. If an effect allows you to search your library for a card with mana value 4 or less, you can't find Assault // Battery.