Pillars of light

Improvise a line that could possibly be
included in the Pillars of Light song but
won't be included because that song is
perfect. Then reveal the top card of
your library and if the card contains one of the
words from the song you may cast it without
paying its mana cost, if it doesn't contain any
words from the song then put the top card on
the bottom of your library and then repeat this
process until you do find one with a word from
the song.