Gogo, Mysterious Mime
Copying legendary creatures has always fought the legend rule: the best clone targets are singular, and duplicating them just sends one copy to the graveyard on the spot. This design writes the exception directly into the copy. When the mime mirrors a creature, it explicitly keeps its own name, so it can become your strongest legend without either version dying. The window is deliberately narrow: a combat-phase, until-end-of-turn arrangement, not a permanent clone, which is why the ability leans on such an aggressive rider. Both the mime and the creature it mirrors get +2/+0 and haste, and both are forced to swing. That mandatory attack is the price the flexibility pays. You are not stamping out a defensive duplicate of a value engine; you are committing two attackers every turn you fire it, whether the board math favors you or not. The trick a shapeshifter usually offers is the choice of what to become; here the interesting part is that it survives becoming it, and that surviving costs a forced attack step. It reshapes a single combat rather than the whole board: a temporary doubling of your best threat bolted to an obligation you cannot take back once the copy resolves.
