Mono-Blue Terror relies on Delver of Secrets and small cantrips to set up Tolarian Terror and Cryptic Serpent, so additional Breath Weapons help answer the 1/1 Delver of Secrets. Breath Weapon deals 2 damage to each non-Dragon creature, so it mainly cleans up the early Delver and other small bodies. Blue Elemental Blast has no legal red targets in their maindeck so it stays boarded out. Our existing plan of grinding card advantage with Ancient Stirrings and resolving big threats is already strong against a deck with few real removal spells. Call Damage Control recoups key artifacts and creatures lost to their Counterspells and Spell Pierce, while Crop Rotation and Barrels are too slow against a deck that can't easily deal with our threats anyway.