Crumbling Vestige

A land that gives you exactly one turn of flexibility, then settles into being a colorless-only source forever after. That single spurt of any color on entry is the whole pitch: it fixes a splash, casts a one-drop off-color, or turns on a hybrid spell the turn it lands, then reverts to producing nothing but colorless mana. The tempo cost is real, since it enters tapped, so it can't also be tapped for mana the turn it arrives. What distinguishes this from the broader family of colorless-fixing lands is how honest the tradeoff is: you are not renting the color over the life of the game, you are buying it once and paying for that purchase in a permanent downgrade to colorless. Wastes with a rider, essentially, and the rider only fires on the way in. That shape makes it a deckbuilding decision rather than a manabase default: it belongs where you need to hit a color exactly once and can live with a colorless land for the rest of the game, most naturally in artifact-heavy or generically-costed shells where the output is not dead weight. It leans on the codified colorless-mana symbol conventions that make this kind of card legible at a glance, and it reads as an experiment in trading long-term fixing for a single guaranteed hit.