Twiddle

Change the tap state of an artifact, creature, or land at the cost of a single card and one mana, and you have one of the oldest design questions in the game written across a single instant. Printed when "tap: do something" was the default ability template and artifacts were the dominant noncreature permanent, the effect did three jobs out of the same trick: untapping a Mox for a burst of mana, tapping a blocker to push damage through, untapping a spent artifact to reuse its activated ability. It was conceived as a fair combat-and-utility instant, a soft Time Walk that happened to slot anywhere. Its lineage runs unusually long. The blue "untap target permanent" school that follows (Turnabout's mass untap, the Paradox Engine breed of combo enablers) works inside the space this card opened. R&D has largely retired the effect at this rate because the applications scale dangerously: untapping a permanent that makes one mana reads as a trick, but untapping a permanent that makes more than one reads as a combo piece, and nothing on the card tells you which world you are in. What it really preserves is an early permission to print flexible one-mana instants without a downside. The design question it asked (how cheap can "change a tap state" be before it breaks?) is one the game has been answering, cautiously, ever since.