Mono-Blue Faeries relies on cheap flying evasive threats and Counterspell/Spellstutter Sprite for protection, so Go for the Throat is efficient removal for their nonartifact creatures like Ninja of the Deep Hours and Faerie Seer. Duress strips their key countermagic before you commit a threat, denying them tempo. Krark-Clan Shaman and Toxin Analysis are weak since their creatures are mostly 1-toughness fliers that dodge ground-based interaction anyway or aren't worth a card to kill. Keep the sacrifice engine as it grinds past their card-neutral disruption over time.