The Dreamcreeper

Cascade (When you cast this spell, exile cards
from the top of your library until you exile a nonland
card whose mana value is less than this spell's mana
value. You may cast that card without paying its
mana cost. Then put all cards exiled this way that
weren't cast on the bottom of your library in a
random order.)
The first instant or sorcery spell you cast until
the beginning of the next end step gains
cascade