Bartemius Crouch Jr.

Whenever Bartemius Crouch Jr. enters the battlefield, exile target creature you don't control
until Bartemius Crouch Jr. leaves the battlefield.
If you do, Bartemius Crouch Jr. becomes a copy
of it.
"Mad, am I? We'll see! We'll see who's mad, now that
the Dark Lord has returned, with me at his side! He is
back, Harry Potter, you did not conquer him — and
now — I conquer you!"