Missing sideboard cards? The full 15-card sideboard runs about $40.83.
Buy sideboard on ManapoolMono Red Madness wants to race, so Weather the Storm is excellent here, gaining 3 life per copy of itself and any prior spell cast that turn via storm, buying crucial time against Lightning Bolt and Fiery Temper. Drown in Sorrow sweeps away Voldaren Epicure and Guttersnipe at -2/-2, cutting off much of their damage engine, though Kessig Flamebreather (a 1/3) survives it. Campfire and Lembas are too slow and low-impact against this clock, and Tithing Blade only trades for one small creature while leaving us exposed. Keep Cast Down and Defile in as they answer Guttersnipe/Flamebreather cheaply.
Dimir Control leans on Counterspell, Snuff Out, and card draw rather than graveyard synergies, so Nihil Spellbomb's exile-graveyard mode is largely dead weight here. Duress strips their Counterspell, Spell Pierce, or removal before we commit our threats, smoothing out our proactive plan. Keep the rest of our removal suite intact since their deck fields real creatures like Gurmag Angler and Spellstutter Sprite that Cast Down and Defile answer well.
Affinity is an artifact-dense deck, and Troublemaker Ouphe's bargained ETB (sacrificing something like an Ichor Wellspring) lets us exile a key artifact like a Giant's Boulder, Cryogen Relic, or an artifact creature before it generates value. Its 2/2 body has no flying or reach, so it can't block their fliers like Kor Skyfisher or Glint Hawk; the exile effect is the reason to play it. Nihil Spellbomb's graveyard-exile ability is low-impact against Affinity's board-based plan, so it comes out. Our existing removal (Cast Down, Unmake, Defile) already handles their Kor Skyfisher and Glint Hawk effectively.