Illusion // Reality

Each split card has two names. If an effect instructs you to choose a card name, you may choose one of those names, but not both.

Each split card is a single card. For example, if you discard a split card, you've discarded one card, not two. If an effect counts the number of sorcery cards in your graveyard, Assault // Battery counts once, not twice.

If you copy a spell that's half of a split card, the copy copies that same half. For example, if you copy Assault, the copy is also Assault, not Battery.