Crystal Vein

A ritual disguised as a land. The first ability is the ordinary colorless tap, the kind of mana any Wastes-style source produces; the second is where the design lives, letting you cash the land in for two colorless at once. That sacrifice clause is the structural trick: it converts a permanent into a burst, trading the long-term mana base for a one-turn spike. The math is deliberately lopsided. A normal land gives you one mana per turn forever; this one offers two mana now in exchange for never tapping it again. So the card is built for decks that want to dump their hand fast and do not care about the back half of the game, the same impulse that drives the fast-mana lands and rituals it shares a lineage with. The cost is built into the timing: spend the burst at the wrong moment and you have simply thrown away a land, which is the friction that earns the upside. It also produces only colorless, which narrows the payoff to artifacts, eldrazi, and cost reducers that do not care about color. What it represents is a clean expression of an idea that runs through the game's whole history: that a land does not have to be a slow, permanent resource if you are willing to let it be a spell instead.