Parasitic Mimic

Flash, First Strike
When Parasitic Mimic enters the battlefield, any
player may choose to lose 4 life. If a player does, sacrifice Parasitic Mimic.
Whenever a creature an opponent controls with toughness greater then Parasitic Mimic's power
enters the battlefield, then Parasitic Mimic's base
power and toughness become equal to that
creatures toughness.