Taskmaster, Mercenary Mimic
Every clone effect answers the same two questions: what do you copy, and when? This one answers "when" with a deliberately restrictive window and "what" with an unusually generous target list. The copy happens at the start of your first main phase, before you attack, before you cast anything, and it locks in until your next turn, so the choice is a once-per-turn commitment rather than a reactive instant-speed pivot the way a flash clone would offer. What pays for that timing rigidity is reach: the target can be a creature already dead in any graveyard, not just something on the battlefield. That single clause turns the ability from a mirror into a soft resurrection engine, letting the body borrow the shape of whatever has already fallen: a fatty that got removed, an opposing bomb that traded, a value creature someone sacrificed. Retained identity balances the generosity. Unlike a plain copy that becomes its target wholesale, this one keeps its own name and stays a legendary Human Mercenary Villain, which matters for anything that cares about names or types and preserves the legend-rule interaction with itself. When the copy expires, the underlying 3/5 is a genuinely durable floor, so a whiffed turn (no worthy target, or the good creature already borrowed) still leaves a resilient blocker rather than a vanilla body. At worst a wall, at best a rotating cast of everyone else's best threats.

