Kloplik, Golem of the Void

Whenever you cast your first spell each
turn, copy it except it has "This spell can't be
countered."
{w}{u}{b}{r}{g}: The next spell you cast this turn
gains cascade. (When you cast that spell, exile
cards from the top of your library until you exile
a nonland card that costs less. You may cast it
without paying its mana cost. Put the exiled cards
on the bottom of your library in a random order.)