This clever interaction relies on purposefully building a creatureless deck, allowing Oath of Druids to relentlessly reveal and dump your entire library into your graveyard during your upkeep. Once your library is completely emptied by that cascading mill effect, Jace, Wielder of Mysteries sits safely on the battlefield waiting to step in. His static replacement ability then transforms what would normally be a fatal draw during your draw step into an instant victory, turning your empty library from a liability into your winning condition.