Racers' Ring

A dual land that eventually becomes a card, with every part of that promise deferred and the deferral doing the pricing. It enters tapped, it fixes for the two colors of a Gruul deck, and then, once a game runs long enough that mana is no longer scarce, it converts itself into a fresh draw. That sacrifice clause justifies running it over the plain tapped duals it otherwise imitates: it is a mana source that stops being one the instant you cash it in. The bill is heavy on purpose. Two generic plus a red and a green, the sacrifice, and the tap is a large chunk of a turn spent to swap a land for a random card, which is why the ability belongs in the endgame rather than the middle turns. What the price buys is a manabase that never truly floods: late, when the worst possible topdeck is another land, this one is a cantrip that happened to fix your colors for the first dozen turns. It belongs to that family of utility duals that trade entering untapped for a stapled-on effect, the kind of land that asks nothing of your spell slots and turns a dead draw into a live one when the game refuses to end.