Prismatic Ending gives flexible exile-based removal that can answer Static Prison, Ajani, Nacatl Pariah, or other cheap nonland permanents they stick, which matters since this is a near-mirror grindy creature fight. Pyroblast stays in the sideboard: it only interacts with blue cards, and Ocelot Pride Midrange plays none, so it would have no legal target. Cabal Therapy is weak here because both players are proactive and symmetrical, so stripping one card rarely swings the game the way it does against combo. Cutting two copies makes room for the extra removal, and Swords to Plowshares plus Prismatic Ending handle their threats more efficiently than trading down.