Zhulodok, Void Gorger

Colorless spells you cast from your hand with
mana value 7 or greater have "Cascade,
cascade." (When you cast one, exile cards
from the top of your library until you exile a
nonland card that cost less. You may cast it
without paying its mana cost. Put the exiled
cards on the bottom of your library in a
random order. Then do it again.)