UBG Reanimator wants to discard a huge threat like Griselbrand, Atraxa, Grand Unifier, or Archon of Cruelty via Faithless Looting, then bring it back with Reanimate, Animate Dead, or Shallow Grave. Leyline of the Void can start on the battlefield for free if it's in the opening hand, and it shuts off their reanimation targets by exiling cards the moment they'd hit their graveyard. Erode is cheap instant-speed removal to answer a reanimated threat if one slips through, and the basic-land search they get back is a minor downside compared to answering a Griselbrand. We cut two Flagstones of Trokair, which offer little here beyond producing white mana, along with the situational flicker/equipment pieces (Flickerwisp and Pre-War Formalwear) that don't interact with their graveyard-centric combo plan.