Implied Adaptation

Exile cards from the top of target player's library
until you reveal an instant or sorcery card, you
may cast that card without paying its mana cost.
Then put all cards exiled this way that weren't
cast on the bottom of that player's library in a
random order.
Implied {u/r} (As an additional cost when
casting this spell, you may pay {u/r}. If you do,
make all choices for this spell including targets
as the spell resolves, not when you cast it.)