Ligma, Mind Goblin

Whenever a player shuffles their library, exile the
top card of that library face down. For as long as
that card remains exiled, you may look at it, you
may cast it, and you may spend mana as though
it were mana of any type to cast it.
{1}{u}{r}: Target player shuffles their library.
"Fetch land? Why don't you fetch..."