The First Sliver (Retro Frame) (MH1-026) - Modern Horizons 1 Timeshifts Etched Foil

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.)
Sliver spells you cast have cascade.