Flow of Possibility

Draw a card.
Cascade, cascade, cascade (When you cast this
spell, exile cards from the top of your library until you
exile three nonland cards whose converted mana
costs are less than this spell's converted mana cost.
You may cast those cards without paying their mana
costs. Then put all cards exiled this way that weren't
cast on the bottom of your library in a random order.)
Storm, storm, storm