"At least for England, the Raven King's got to show back up again if he wishes to take away English magic. He's the only mystical force capable of reshaping the world to that extent which I know of."

There's a yearning in Strange's tone of voice as he mentions the Raven King. Obviously he wouldn't want his magic to vanish, but the idea of meeting, of even catching a glimpse of the Raven King is tantalizing.