Mono-Blue Faeries is entirely blue, making Red Elemental Blast and Pyroblast maximally effective, countering Counterspell or destroying any of their many 1-2 toughness fliers like Faerie Miscreant, Faerie Seer, Spellstutter Sprite, or Snaremaster Sprite. Fireblast's Mountain sacrifice cost is a liability against a fast, flying tempo deck since you need every land to keep casting spells, so trim one copy for more interaction. Prioritize racing their small fliers with burn to the face while using the Blasts to remove blockers or evasive threats and fight through Counterspell. Sazacap's Brew and Highway Robbery are too slow against this tempo-oriented deck, so cut them for the proactive Blast package.