Mystique

{x}{u}, Choose Target Creature with a converted
mana cost of X and Put a Mystique Token into
play. Treat that Token as a copy of that Creature.
{u}{r}, Choose a Creature Token you control:
Mystique Becomes a Copy of That Creature
until she changes target.
"It should be wonderful to be able to become whoever
you want to become." -Alexa