This is a race between two combo decks, so speed matters more than interaction. Pyroblast and Crumble offer efficient answers to their blue spells and artifacts, while the second Chain of Vapor bounces a landed Dreadnought or Powder Keg for a turn to buy time. Arcane Denial is weak here since giving Stiflenought extra cards accelerates their combo assembly even further. Prioritize goldfishing your own kill over trying to counter their Stifle-protected Dreadnought.