Shifting Borders is a uncommon Instant — Arcane card from Saviors of Kamigawa (SOK), collector number 56. Current market price: $0.33 (foil $3.14), TCGplayer market prices via Scryfall.
Exchange control of two target lands. Splice onto Arcane {3}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)