Millikin

Self-mill reframed as resource economy rather than a graveyard-filling end in itself: each tap converts a card from your library into one colorless mana, so the deck pays for ramp in cards instead of life or tempo. That trade rethinks a mechanic early designs mostly treated as a clock or as raw fuel. Here, milling yourself is the cost, not the payoff, and the payoff is plain colorless mana, which makes the card read as a mana rock that happens to dig. The 0/1 body is irrelevant to combat and exists only to be a creature that can be sacrificed, animated, or recurred, but the structural idea is what gives it staying power: in a graveyard-matters shell, the "cost" of self-mill is no cost at all, because the cards heading to the bin are exactly what you wanted there. Reanimator, threshold builds, and decks that loop creatures from the yard all get a rock that doubles as an engine input. The tension it resolves is that ordinary mana rocks give you mana and nothing else, while this one bundles mana and graveyard depth into a single activation, asking only that you build a deck where thinning your library is upside. A modest creature pulling double duty, and the double duty is precisely why it has outlived its origins.