Mishra's Workshop

Three colorless mana for a tap, restricted to artifacts only: the rate sits so far outside the curve that the card has effectively defined every format it has touched by being banned or restricted in it. The design lineage is the Power Nine school of land, a fixed-color (here, colorless) burst that breaks the one-mana-per-land axiom Magic's economy is built on, with a narrow spend clause meant to contain the damage. The clause did not contain it. Artifacts as a card type span every cost, every effect, and every color identity, so "spend only on artifacts" reads as a restriction and functions as a green light. The Workshop decks of Vintage are the natural endpoint: a turn-one Lodestone Golem, Sphere of Resistance, or Trinisphere on the play, with the Workshop itself producing more mana than the lock pieces cost to deploy. The asymmetry is the whole point. Because the Workshop player is paying for prison artifacts that tax everyone, the restricted mana funds exactly the strategy that punishes the opponent's mana most, while the Workshop's own three colorless never feels the tax it imposes. Reprinted only in premium and From the Vault style products, never in a Standard-legal set: the card is a museum piece the Reserved List keeps in amber, and the format it shaped is the only one that still lets it off the leash.