Mono-Blue has almost no creatures, so Armageddon does little to disrupt them while symmetrically wrecking our own board; cut it along with a couple Rishadan Port since their tempo plan is countermagic, not aggression. Bring in the full set of Pyroblast to blow out Counterspell, Daze, Foil, Thwart, and Arcane Denial, or to destroy key blue permanents like Stasis. Naturalize gives another way to destroy Stasis or Powder Keg, both of which can lock down or blow up our threats. Keep Sylvan Library and Weathered Wayfarer as the core card-advantage and land-fixing engine, and lean on Terravore and Werebear to grind through countermagic since Mono-Blue struggles to interact with resolved threats once they're down.