Phyrexian Dreadnought does not die to Pyroclasm's 2 damage since it has 12 toughness, and hitting it before the sacrifice trigger resolves is irrelevant since Pyroclasm cannot kill the 12/12 once it's on the battlefield. Cursed Totem does not shut off Stifle-adjacent shenanigans and stops nothing here, but more importantly it isn't a great include if they have no activated creature abilities of note, so consider it a low-priority swap. Armageddon remains excellent since this deck has no way to rebuild lands quickly, though Wasteland cannot target their all-Island manabase since Islands are basic lands. Naturalize is not dead since Phyrexian Dreadnought is an artifact worth targeting.

Pyroclasm wipes their Jackal Pups, Grim Lavamancers, and Mogg Fanatics for two mana, a huge tempo swing against a low-toughness aggro shell. Aura of Silence taxes and can destroy their Cursed Scroll and Seal of Fire, both recurring damage sources that are hard to otherwise interact with. Wild Mongrel folds to their removal-heavy burn suite (Incinerate, Lightning Bolt) too easily to be worth the slot here. Armageddon is still strong since it can reset a race where you're racing their burn plan with bigger threats.

Aura of Silence taxes their enchantment-heavy plan and can destroy Sterling Grove, Enchantress's Presence, or Solitary Confinement outright, directly attacking their engine. Ray of Revelation is a cheap second answer to Serra's Sanctum-enabling enchantments or Solitary Confinement, with flashback as insurance. Pyroclasm does almost nothing since their creature count is minimal (Argothian Enchantress is a 0/1 that dies to it, but that's a marginal upside), so it comes out in favor of more enchantment removal. Keep Armageddon and Wasteland in as premier disruption against their Serra's Sanctum/Windswept Heath-based mana base — landing Armageddon before they assemble Sanctum is often game-winning.