Hi. If I cast dream salvage and stack an ability onto it, and that ability makes my opponent discard cards, will my dream salvage, once resolved, draw me cards from the stacked discard ability? (Jace's Archivist combo)
Yes. Dream Salvage determines how many cards you draw when it resolves. Any cards the targeted opponent has discarded up until that point in the turn will count, including cards that the player discarded after you cast Dream Salvage.
Dream Salvage