Atnus, the Grand Archaeus

When Atnus, the Grand Archaeus enters the
battlefield, return up to one target instant
and/or sorcery card from your graveyard to
your hand.
{u}, {t}: Exile any number of cards from your
hand face down. Put that many cards from the
top of your library into your hand. Then look
at the exiled cards and put them on top of your
library in any order.