Are you going to try to bring the Gods online with devotion?  At least, Erebos?  I think you should remove at least 2 copies of Drown in Sorrow for the Whip or Erebos if so.  Going to be hard to keep your dudes alive.  Also, what do you think about 1-2 Chandra to prevent a blocker for Master?  You also get the opportunity to get a little more card draw.  Just some thoughts.  Looks centered to counter the meta of mono U or B right now, and it should do that well.

update your sideboard to remove grafdiffers and sever as they rotate out.