Riftstone Portal

Most lands earn their zero cost by tapping for mana; this one earns it by being most valuable when it never enters play at all. The on-battlefield mode is deliberately inert: a colorless tap-land that does nothing your other lands cannot. The functional ability is a graveyard-only static effect that grafts a green-or-white dual ability onto every land you control, inverting the usual relationship between a card and the discard pile. A land you would otherwise never want in hand becomes one you actively want to pitch. Any deck with discard outlets or self-mill turns it into fixing without ever spending a land drop on a dual source, and the granted ability leaves your real lands free to make colorless when you need it. The design comes from an early-era school of thinking that treated the graveyard as a second battlefield, projecting a continuous effect from a zone most cards only pass through on their way out. The trade it resolves is the tempo cost of color fixing: rather than tapping a dual land and committing a slot to it, you fix off a discard you were making anyway and keep your manabase untouched. The fragility is genuine (graveyard hate switches it off, and exiling it from the bin removes the fixing outright), but for a deck already stocking its yard, it is correction that costs no battlefield presence at all.