I have Oskar Rubbish Reclaimer on board. I discard Counterspell to cast it. Then I discard Shadow of the Grave and cast it. What cards are returned to my hand?
When you cast Counterspell from your graveyard after discarding it, it becomes a new object leaves the graveyard (and again when it returns there). This means that it's not a card you discarded this turn, according to Shadow of the Grave and won't go back to your hand.
















