UBG Reanimator relies on Animate Dead, Shallow Grave, and Reanimate to cheat Griselbrand, Atraxa, or Archon of Cruelty out of the graveyard, so Faerie Macabre lets you exile their discarded reanimation targets (from Faithless Looting or Unmask) before they can bring them back, while still being a cheap Aluren-eligible flying creature. Veil of Summer protects your hand from Thoughtseize, Unmask, and Collective Brutality discard, letting your combo pieces survive their disruption-heavy start. Omniscience and extra Acererak copies are too slow against a deck that can reanimate a 7/7 flier as early as turn 1-2, so they come out in favor of proactive, cheap answers. Your own Aluren/Show and Tell plan remains the priority since racing their graveyard plan outright is usually faster than trying to out-value it.