Maelstrom Nexus

The first spell you cast each turn has cascade.
(When you cast your first 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.)
Maelstrom Nexus can be your commander.
-(Brandon Sanderson Cube Legendary)-