Grixis Reanimator is racing you to the same plan with Unearth and Persist bringing back Archon of Cruelty or Emperor of Bones, so Mystical Dispute is cheap interaction against their blue spells like Thought Scour and Spell Pierce while protecting your own reanimation turn. Surgical Extraction is strong here, letting you exile a discarded Archon of Cruelty or Abhorrent Oculus out of their graveyard before they can Unearth or Persist it back. This is a mirror-style race, so Thoughtseize and Force of Negation remain essential to strip or counter their reanimation spells on the crucial turn. The card selection spells are too slow when both decks are racing to resolve a huge reanimated threat, so they're cut for interaction.