Cursed Mirror

Two roles fused into one artifact: a red mana rock and a clone that leases a body off the current board for a single turn. Because the copy uses a replacement effect (the shape is chosen as the artifact enters, so it never touches the stack and there is no window to respond), it reads the battlefield the instant it arrives and hands you a hasty version of whatever is worth copying. The creature you copy does not have to be an opponent's. Copy your own creature and you retrigger an enters-the-battlefield ability, double a combat threat, or fetch a combo half at instant availability; steal an opposing finisher and you point it back across the table for a swing. When the turn ends the borrowed form falls away and you are left with a permanent that taps for red, which is precisely what lets the copy half afford to be greedy: a board with nothing worth copying still leaves you a functioning rock, not a dead draw. It plays like a self-fueling Phyrexian Metamorph that rents a body instead of owning one, then settles back into mana production. The residual red is the part that never reverts. The body is on loan; the mana stays.