Stiflenought wants to protect a turn-one Phyrexian Dreadnought or simply counter everything you do, so Xantid Swarm is excellent — it stops Stifle, Vision Charm, and any counterspell from resolving for a full turn cycle while you assemble Hermit Druid or Survival plays. Duress strips their key protection piece (Vision Charm, Stifle, Misdirection) or a Dreadnought before it matters, clearing the way for your combo. Cut clunky mana-hungry cards like Palinchron and Darigaaz's Caldera that don't advance your plan fast enough against this speed, along with situational graveyard recursion that's less relevant when you need to race. Prioritize resolving Survival of the Fittest or Hermit Druid through their counterspell-dense shell rather than grinding — this matchup is about beating them to the punch.