WU's key interaction and threats are blue, so Pyroblast is premium, countering Force of Will, Daze, Stifle, or Consign to Memory, or destroying a resolved Quantum Riddler. Redirect Lightning can change the target of a single-target spell like Swords to Plowshares, pointing their removal at another creature instead of your key one. Chrome Mox costs you a card to imprint, so trim it along with excess Eldrazi Confluence for more reactive cards. Keep Trinisphere and Chalice of the Void in, since they punish their one-mana cantrip suite and Daze heavily.