Idulon Mind Thief

Flash
When Idulon Mind Thief enters the battlefield, search target opponent's library for
an instant or sorcery spell and exile it. Then shuffle his or her library. As long as that spell remains in exile, you may cast it and you may spend mana as though it were mana of any color
to cast it. Whenever you cast that spell, put it into its owner's hand as it resolves.