Sequestered Stash

A colorless source that pays its keep twice: it taps for mana like any other land while it sits on the battlefield, then converts itself into a four-mana graveyard search once the artifacts you wanted to recur have died or been milled. The mill-five is engine and cost at once: it digs five deep for the best target while potentially burying more artifacts into the yard on the way down, which rewards decks that actively fill the graveyard rather than ones that hoard cards in hand. What it really does is launder a tutor through the bin. Instead of pulling an artifact straight to hand, it stacks one on top of your library, so the recursion costs you a draw step and a measure of tempo: that sacrifice clause is what keeps a land that taps for mana from doubling as a free repeatable tutor. The delay is the whole balancing act. Any deck building toward a single key artifact can slot it as a colorless land that doubles as insurance against removal, since it demands nothing of the manabase and asks only that the graveyard hold something worth digging back up.