Sorting Hat, Songs Crafter

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 if the resulting
spell's mana value is less than this spell's mana value. Then put all cards exiled this way that
weren't cast on the bottom of your library in a random order.)