Gemstone Mine

A finite five-color land, which is the design idea that lets it be untapped. The wager is exposed in the counters: three perfect-fixing taps, then the land eats itself. Where the painlands of the era charged you life for color access and the original dual lands cost a slot in the reserved-list lottery, this one charges duration. You get the cleanest mana imaginable for the first three turns it matters, and then it is gone, which makes it a deckbuilder's tool for the part of the game where color requirements are tightest; the late game where you no longer care about a land slot is somebody else's problem. The counter mechanic also fences the card off from the loops that would otherwise break a free, infinitely repeatable rainbow source: each tap is a tick toward sacrifice, so it cannot quietly fuel a mana engine forever. That restriction is what keeps it honest in formats fast enough to spend three counters before the clock runs, and it is exactly why it has never needed the leash that the truly free fixers eventually earned. What it argues is a thesis on resource shape: not every land has to be permanent, and the ones that are not can afford to be perfect.