Your search for "The First Sliver 1371" revealed the following:
The First Sliver - Retro Frame (Etched) (RMH1) from Modern Horizons 1 Timeshifts, available at 401 Games Canada. Rarity: Mythic Rare Finish: Foil Artist: Svetlin Velinov Card Text:CascadeSliver spells you cast have cascade.