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When a fused split spell resolves, follow the instructions of the left half first, then the instructions on the right half.

If a player names a card, the player may name either half of a split card, but not both. A split card has the chosen name if one of its two names matches the chosen name.

If you cast a split card with fuse from your hand without paying its mana cost, you can choose to use its fuse ability and cast both halves without paying their mana costs.