Grixis Reanimator's whole plan runs through the graveyard — Faithless Looting and Thought Scour fuel Unearth and Persist to cheat Archon of Cruelty or a returned Persist creature into play, so Nihil Spellbomb is a premium answer that strips their graveyard before those recursion spells find a target. Damnation is excellent insurance against a resolved Archon of Cruelty or Abhorrent Oculus manifest army, wiping their board in one card. Spell Snare only hits Thought Scour and a couple of their two-drops, so it's replaced with more impactful graveyard disruption; Cling to Dust stays largely as-is since exiling their graveyard on the way to gaining life or drawing a card is still relevant here. Prioritize Fatal Push and Counterspell on Psychic Frog and Abhorrent Oculus before they take over the game, and hold Force of Negation for Unearth or a reanimation spell.