Psionic Portal

Cascade (When you cast this 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 in a random order.)
Whenever you cast an Instant or Sorcery spell while Psionic Portal or another spell is on the stack, copy that spell. You may choose new targets for the copy.