Omnath, Archon of Elements

You may spend {g} as though it were mana of
any type.
Surge — Whenever a land enters the battlefield
under your control, if it's not the first land that entered under your control this turn, cascade.
(Exile cards from the top of your library until you
exile a nonland card that costs less than this card.
You may cast it without paying its mana cost. Put the
exiled cards on the bottom of your library in a
random order.)