You Shall Not Pass

Exile target attacking Mordor Creature, that
creature's controller searches his or her library for
a basic land and puts it into play, then shuffles
his or her library.
"You cannot pass! I am a servant of the Secret Fire, wielder of the flame of Anor. The darl fire will not
avail you, flame of Udun. Go back to the Shadow!
YOU! SHALL NOT! PASS!".
—Gandalf the Grey