Rulings

• Domain abilities count the number of basic land types among lands you control, not how many lands you control or how many of any type.2021-06-18
• The basic land types are Plains, Island, Swamp, Mountain, and Forest. Land types other than basic land types (such as Desert) don't contribute to domain abilities.2021-06-18
• You do what the spell says in order, so you'll put a new basic land card onto the battlefield before you determine the value of X.2009-02-01
• Exploding Borders will still deal damage even if you don't put a land card onto the battlefield.2009-02-01
• Exploding Borders has only one target: the player. If that player becomes an illegal target by the time Exploding Borders would resolve, the entire spell doesn't resolve. You won't get to search for a basic land card.2009-02-01