Valiria, Who Scorches Earth

When Valiria, Who Scorches Earth enters the
battlefield, if an opponent controls more lands
than you, search your library for a Mountain or
Plain. Put that card onto the battlefield tapped,
then shuffle your library.
Whenever a nonbasic land an opponent controls
is put into a graveyard from the battlefield, exile
the top card of your library. You may play that
card this turn.