Omnath, Locus of Chaos

When Omnath, Locus of Chaos enters the
battlefield, search your library for a land card,
put it into your hand, then shuffle.
You may play an additional land on each of your
turns.
{w}{u}{b}{r}{g}: Exile the top card of your library.
You may play it this turn without paying its
mana cost. Spells cast this way have Cascade.