Room of Requirement

{1}{u}: Exile target permanent you control
underneath this card
{1}{w}: Return target permanent exiled by this
card to the battlefield
-
"Dobby knows the perfect place, sir! Dobby heard tell
of it from the other house-elves when he came to
Hogwarts, sir. It is known by us as the Come and Go
Room, sir, or else as the Room of Requirement!"