Temperamental Waveform

{w}{u}: Exile target land you control, then return
that card to the battlefield under its owner's
control tapped.
Landfall - Whenever a land enters the
battlefield under your control, you may reveal
the top card of your library. If it's converted
mana cost is less than or equal to the number of
lands that entered the battlefield this turn, put it
into your hand. Otherwise, put it on the bottom
of your library.