UBG Reanimator lives and dies by its graveyard, using Faithless Looting, Reanimate, Animate Dead, and Shallow Grave to cheat Griselbrand, Atraxa, Grand Unifier, and Archon of Cruelty into play, so Rest in Peace is a devastating answer that exiles their graveyard on entry and shuts off every reanimation spell going forward. Surgical Extraction can proactively strip a Reanimate or Animate Dead once discarded, cutting off their reanimation targets' path back. Force of Negation is weaker since their key spells (Reanimate, Animate Dead, Shallow Grave, Unmask) are often simply too cheap to matter, and Spell Pierce doesn't stop a resolved reanimation spell once the creature is already back.