Imperious Mindbreaker

Mill spells usually count in fixed increments: five here, seven there, a rider that empties a fixed slice of the library. This one instead scales the clock to a body's toughness and then, through soulbond, doubles the point of contact. Pair it with a fat blocker and each attack from either creature strips cards equal to its own toughness, so the mill total is defense-side stats routed into an offensive win condition, an unusual conversion for a mechanic that normally lives on evasive attackers or noncombat effects. The 1/4 frame is doing real work: it survives most early combat, its own attacks bite for four, and it wants to be plugged into a durable partner rather than a fast one. Soulbond's persistence clause matters too, since the pairing (and the mill grant on both creatures) holds only while you control both, turning the whole engine into something an opponent can pull apart by killing either half rather than a single removal target. Toughness-matters mill is a narrow enough seam that few cards sit in it, which makes this a specific answer to a specific deckbuilding question: how do you turn a wall into a milling threat without asking it to hit hard? The answer is to measure the clock by how well the creature stands still, not by how fast it swings.