Treachery

The genius of the design is the untap clause, which is what separates this from every other steal-a-creature spell ever printed. Control Magic and its descendants cost you the tempo of their mana investment; you tap out, take the creature, and pass. Here the five-land untap refunds the entire cost the moment the Aura resolves, turning a five-mana commitment into something that effectively costs nothing but the card itself. That refund window is the whole story: it leaves you with mana up to counter, to protect the theft, to deploy another threat, or to chain into a second steal. The "up to five" wording is the only restriction, and in practice it is no restriction at all, since the cost is exactly five and most lands tap for one. What was meant as a balancing rider became the engine that made the card a permanent free spell. The untap also rewards greedy curves: cast it off five tapped lands and you have not spent anything you can feel. That combination of permanent control and zero net tempo is why it has never seen a serious reprint at common power levels and why it remains the high-water mark for creature theft, the card every later "steal a creature" effect is implicitly measured against and deliberately weakened from.