Can Silent Gravestone prevent someone from casting an Aftermath spell from the graveyard?
If you cast Memory from a graveyard, nothing is targeting a card in graveyard. Therefore Silent Gravestone won't prevent you casting Memory. When Memory resolves, both players shuffle their hand and graveyard into their library, then draw seven cards. Silent Gravestone only prevents the casting of a spell (or ability) that targets a card or cards in a graveyard.