Mainboard (60)
Creatures (6)
Instants (16)
Artifacts (17)
Enchantments (3)
Lands (18)
Sideboard (15)
Mono-Red Madness wins by overwhelming you with cheap burn spells and damage-on-spell triggers from Guttersnipe and Kessig Flamebreather before your food engine can stabilize; your primary goal is to survive long enough for Cauldron Familiar recursion and Lembas/Nutrient Block to bury their burn in life totals. Weather the Storm is your best sideboard card here — cast it after they unload spells and you will frequently gain 6-10 life for two mana, which can completely swing a game. Drown in Sorrow is a clean three-mana sorcery that kills Guttersnipe, Sneaky Snacker, and Voldaren Epicure in one shot, removing the damage-multiplier threats that make their burn sequences lethal. Nihil Spellbomb, Tragic Slip, Tithing Blade, Heritage Reclamation, and Heaped Harvest all either answer problems you won't face against a mono-red deck or are too slow for a matchup decided in the first five turns. Pestilence stays in because, once you're stable on life, it can lock out their small creatures and grind the game entirely.
Grixis Affinity is a fast artifact-based deck that wins through card advantage from Thoughtcast and Ichor Wellspring, backed by Galvanic Blast for reach and Myr Enforcer as a massive threat. Pestilence is your best card in this matchup — it can repeatedly wipe their board of small creatures like Refurbished Familiar and Utrom Monitor while your Cauldron Familiar keeps you alive, so protect it at all costs. Snuff Out provides free interaction for their large threats in the mid-game, and Faerie Macabre hedges against Blood Fountain recursion as a recastable body. Duress comes in to strip Galvanic Blast or Makeshift Munitions before they can set up a lethal turn, and also hits their interaction pieces game two when they bring in Metallic Rebuke. Nihil Spellbomb and Tragic Slip are trimmed because the Spellbomb is redundant with Faerie Macabre at a worse rate, and Slip requires a death trigger that may not line up on curve against their fast artifact creatures.
Dimir Terror is a tempo-control deck that wins by filling the graveyard to fuel cheap threats like Tolarian Terror and Gurmag Angler, backed by Counterspell and Snuff Out. Duress comes in to strip countermagic and Snuff Outs before they can answer your threats or disrupt your engine. Snuff Out gives you unconditional removal that can't be countered by Blue Elemental Blast and handles the large delve creatures efficiently. Faerie Macabre provides instant-speed graveyard hate that dodges countermagic entirely, shrinking or blanking Tolarian Terror and Gurmag Angler when cast at the right moment. Tragic Slip is too conditional against large graveyard-fueled creatures, and Nihil Spellbomb is replaced by the more proactive Faerie Macabre since the Spellbomb's draw trigger can feed their graveyard setup.