Candelabra of Tawnos

A one-mana artifact whose untap clause was priced as if lands were a fair resource to untap, which they almost immediately turned out not to be. The design assumes the symmetry of the activation cost (you pay X to untap X lands) closes the loop: you spend mana to get mana back, net zero on the lands themselves, with the tap and the artifact as the friction. What the design did not account for is lands that produce more than one mana. Point the activation at Tolarian Academy, a board of Cloudposts, a Gaea's Cradle, or the karoo bouncelands that yield two mana apiece, and the X-for-X exchange inverts into a mana engine that scales with whatever the rest of the deck has assembled. The card has spent most of its life as the converter at the heart of high-power combo shells built around big-mana lands, the piece that turns a field of tapped lands into a fresh, untapped one and, with the right multipliers, into arbitrary mana. Few cards demonstrate so cleanly how a cost-symmetry that looks airtight in isolation can shatter the moment the environment around it changes. The rate (one mana, no color, no restriction on which lands) is what makes it dangerous; the activation's apparent elegance is what kept it from being seen coming.