Quicksolver Gargantuan

When Quicksolver Gargantuan enters the battlefield, investigate.
{t}, Sacrifice a Clue: Exile the top card of
your library. If it's an instant or sorcery spell,
you may cast it this turn without paying its
mana cost.
"Some riddles were not meant to be answered by man. Fortunately, we have machines for those ones."
—Urza Planeswalker