Ebony Fly

A flying carpet reimagined as a bug: the premise is a Mordenkainen-style familiar that starts life as a plain colorless rock and would rather be a beater. What makes it tick is the randomness bolted onto the top end. The four-mana activation is a mana sink that animates the artifact into a creature whose size is whatever a d6 rolls, anywhere from a 1/1 to a 6/6 flier for the turn, so the ceiling is real but never something you can build a lethal turn around; you commit the mana and take what the die gives. Any roll produces a body, so there is no whiff at the die itself. That the animation carries no timing restriction is where the card earns a little more than its rate: you can hold the four mana open and roll it on an opponent's turn to ambush a swing with a surprise flying blocker, since the "until end of turn" clause covers a defensive activation fine even if it forecloses using the same trick to attack off-turn. The attack trigger only fires when the Fly itself is in the red zone, so the order is fixed: roll the die on your turn, then let the resulting flier hand evasion to another attacker. The whole package sits in the artifact-that-becomes-a-creature corner of the color pie, priced cheap because every relevant thing it does costs more mana on top and cedes part of the outcome to a die.