Field of Forgotten Emperors

(Field of Forgotten Emperors enters the
battlefield tapped.)
{t}: Add {w} or {g}.
Whenever you cast a creature spell, you may pay
{w}{g}. If you do, create an Imperial Lily token.
{1}{w}{g}, {t}, Sacrifice an Imperial Lily token:
Search your library for a green and/or white
creature card, reveal it, put it into your hand,
then shuffle your library.