Cage is bad. IMO when it comes to gravehate hate. It's either leyline or surgical. Surgical in snapcaster based decks and leyline in combo decks. Why? Because of opponents discard/countermagic. Leyline dodges both discard and Force of Will which makes it such a powerful card. It sucks to draw into it late, but it's just so much better than grafdiggers cage. If the dredge player goes crazy on the play and flips a bunch of therapies, grafdiggers cannot help you.

I'd play:
4 leyline of the void
4 leyline of sanctity
3 blood moon
3 echoing truth
1 reb

Oh and blood moon is simply better because it hoses rug Delver. Bolt/fire/ice can still deal with magus, and they regularly keep them in from my experience.