Grixis Reanimator wants to fill the graveyard with Faithless Looting and Thought Scour before Persist brings back Archon of Cruelty (or Unearth retrieves a cheaper threat like Abhorrent Oculus or Psychic Frog), so Tormod's Crypt and Nihil Spellbomb are premium — exile their graveyard right before they try to reanimate, shutting down Persist and Unearth targets alike. Abhorrent Oculus also needs six cards exiled from their own graveyard as an additional cost to cast, so emptying their graveyard shuts that threat down too. Thoughtseize strips Unearth, Persist, or a discard outlet before they can set up, and also gives us crucial information about their hand. Keep pressure on since Psychic Frog and Fatal Push can grind if the game goes long.