Eldrazi's Chalice of the Void can lock us out of Lotus Petal, Brainstorm, and Ponder on 0 or 1, so Abrade gives us cheap, flexible artifact removal to destroy a Chalice before it taxes us. Brotherhood's End's artifact-destruction mode can hit multiple Chalices or Eldrazi Spawn-generating permanents at mana value 3 or less in one sweep. Grafdigger's Cage stops Reality Smasher and other creatures from re-entering via any recursion while not hurting our own Sneak Attack plan since our threats are cast, not cheated from the graveyard. Omniscience is too slow and vulnerable to Chalice disruption, and Flusterstorm has few good instant/sorcery targets in their creature-heavy list.