Mono-White Initiative runs Chalice of the Void which can lock our low-cost spells, so Abrade gives us a way to destroy it (or another key artifact) outright. Aether Spellbomb offers a cheap bounce effect that dodges Chalice at X=0 setups since its mana value is 1 and can later be sacrificed for value or a bounce on a problematic Thalia, Guardian of Thraben or Archon of Emeria. Pithing Needle can shut off Karakas' bounce ability or another key activated ability. Since Wasteland and Chalice punish our fast starts, we keep the plan lean rather than diluting with more narrow answers.