Aura of Silence is our best addition here. It makes their artifact spells, like Phyrexian Dreadnought and Powder Keg, cost {2} more, and it can be sacrificed to destroy an artifact such as Powder Keg before it builds up fuse counters. That covers the same targets as the main-deck Naturalize while also taxing their threats, so two Aura of Silence replace the two main-deck Naturalize. Sphere of Resistance is already in our main deck and makes every spell cost {1} more, which squeezes their counterspell-heavy, cantrip-heavy draws and slows their Stifle and Dreadnought plan. Keep Swords to Plowshares in to answer a resolved Dreadnought before it attacks. Thermokarst stays in as well, since their Islands are legal land destruction targets.