Hydroblast is excellent here, countering any red spell (including Fiery Temper and Lightning Bolt) or destroying red permanents like Kessig Flamebreather and Guttersnipe. Drown in Sorrow's -2/-2 wipes Voldaren Epicure, Kessig Flamebreather, and Guttersnipe all at once, severely disrupting the damage engine. Counterspell comes out since it's too slow and mana-hungry against a deck that wants to race; Brainstorm is cut because it does nothing to stop the clock. Relic of Progenitus can strip their graveyard to slow down Lava Dart and Faithless Looting flashback, though it won't stop madness-cast Fiery Temper since those are cast from exile.

This is a mirror-ish grindy matchup, so protecting your key threats and countermagic with Dispel (counters their Counterspell or removal instants) matters more than extra removal. Annul can stop their Spellstutter Sprite (an artifact? No, Spellstutter Sprite is a creature, so Annul won't hit it) - instead Annul is kept mainly as a late addition against any artifacts they bring in, but with limited targets here it's a weaker include; still worth a couple copies for flexibility against Maestros Theater adjacent plans is minimal, so trim to fewer. Cast Down is cut since their creature base (Ninja of the Deep Hours, Augur of Bolas, Faerie Seer) is low-impact and removal is better spent on bigger threats. Plunder the Trollshaws is cut as card selection is less valuable than disruption in this attrition war.

Affinity's board is full of cheap small creatures like Kor Skyfisher, Glint Hawk, and Refurbished Familiar, so extra copies of Cut Down (destroys any creature with total power+toughness 5 or less) efficiently answer most of their threats. Dispel is low-value here since their deck is mostly creatures and artifacts, not instants — reconsider: remove Dispel from the plan since it has few legal targets. Replace with Cut Down and keep Cast Down and Snuff Out as primary removal; trim slower card-selection pieces like Plunder the Trollshaws and the narrow Extract a Confession for more interaction.