Pyroblast and Red Elemental Blast are strong against an all-blue deck because nearly every spell they cast is blue. They can counter Counterspell, Foil, Gush, or any other blue spell, which helps your burn and threats resolve. Be aware that they cannot touch Phyrexian Dreadnought, since it is a colorless artifact creature and neither card's destroy mode can target it. Tormod's Crypt is a free artifact that can exile their graveyard to shut off the flashback on Flash of Insight without costing tempo. Sulfuric Vortex is too slow and also damages you, and Urza's Bauble doesn't meaningfully affect their plan. Race aggressively and keep Pyroblast or Red Elemental Blast mana up to counter their key blue spells, since you can't answer a resolved Dreadnought with these cards.