Leyline of the Void is very strong since it can be free pregame and completely shuts down their reanimation-adjacent lines if they ever put Emrakul, the Aeons Torn or Atraxa, Grand Unifier into the graveyard, without disrupting your own deck at all. Shallow Grave is too slow and exposes a creature to their Force of Will-backed Show and Tell into Omniscience plan without pressuring it, so it's cut for a more proactive disruption piece. The extra Collective Brutality adds another way to strip Show and Tell before they combo off. Prioritize using Thoughtseize and Unmask proactively to strip their combo pieces since they have very little actual removal for your threats once they resolve.