Ghostfire Blade

The discount clause is the whole engineering problem solved in one line. A +2/+2 equipment for one mana reads underpriced until you reach the equip cost: three to move it is steep enough that on an ordinary green or white creature it plays like a sunk investment, a rate that never earns its slot in a real deck. Strip the color off the creature, though, and the equip falls to one. That single subtraction changes the arithmetic completely: you can re-suit a fresh threat every turn for trivial mana, which is precisely the tempo a board of colorless beaters is built to spend. The conditional is the card. It is a sword forged for one kind of army, inert to everyone else, and viciously efficient inside its lane, where the +2/+2 stacks onto an aggressive curve and the near-free equip lets you rebuild after a sweeper without bleeding tempo. It sits in a small family of designs that gate a strong effect behind a deckbuilding restriction rather than a mana tax: you pay the cost in homogeneity, not in resources. Read cold, the numbers look mediocre; read inside the artifact-and-Eldrazi shell it was made for, it is one of the cheapest ways colorless aggression has ever had to turn small bodies into a clock.