Evanescent Intellect

Mill grafted onto a body, where the host's combat stats are beside the point. This Aura turns whatever creature it sits on into a repeatable mill outlet, three cards at a time for one and a blue, and it does not care whether the enchanted creature is a wall or a beater: its job becomes the activation, not the attack. That separation is the design idea worth pausing on. Early mill outlets tended to be one-shot spells or self-grinding artifacts and lands; here the engine lives on the battlefield, which means it inherits everything that comes with being a creature. The host can be deployed early, kept untapped behind defenders, and tapped for value turn after turn, but it also dies to any removal spell or combat trade, and the Aura dies with it. The governor is the tap symbol in the granted ability: without an untap effect, one activation per turn is all the creature offers. That ceiling is not fixed. Any way to untap the enchanted creature between activations lets you spend more mana on the same body and grind faster, since each fresh untap resets the tap cost. The fragility cuts the other way: it is card disadvantage waiting to happen, two permanents answered by one removal spell, which is the price of putting your engine somewhere the opponent can shoot it.