“Grixis Affinity is a tempo-combo deck that leverages free or cheap artifacts — particularly artifact lands and cyclers like Ichor Wellspring — to rapidly reduce the cost of Myr Enforcer and Refurbished Familiar to zero mana, flooding the board with large threats ahead of curve. Thoughtcast and Reckoner's Bargain provide card velocity to chain resources together, while Galvanic Blast serves as both removal and a finisher, easily achieving metalcraft for four damage. The deck wins by overwhelming opponents with cheap, efficient threats backed by strong card draw and burn before fair decks can establish their gameplan.”
Missing sideboard cards? The full 15-card sideboard runs about $56.75.
Buy sideboard on ManapoolPyroblast stays home: it only hits blue cards, and their only blue card is Sneaky Snacker, which a deck of Mountains never casts, so there is nothing to counter. Cast into the Fire deals 1 damage to each of up to two target creatures, which kills Voldaren Epicure and Sneaky Snacker. Snacker goes to the graveyard and can come back when they draw a third card in a turn, so don't count it as permanently answered. Alternatively, the spell can exile an artifact such as a Blood token to slow their looting and madness enablers. Krark-Clan Shaman comes out because its damage can't touch flying Snackers and it costs us artifacts we want for affinity. Cast Down stays in as clean removal for Kessig Flamebreather and Guttersnipe. We're the beatdown here: race with Myr Enforcer and Refurbished Familiar while using Galvanic Blast and Cast into the Fire to pick off their small payoff creatures before Kessig Flamebreather and Guttersnipe take over.
Pyroblast is excellent here, countering Counterspell, Dispel, Brainstorm, and Lorien Revealed or destroying Spellstutter Sprite, Faerie Seer, Ninja of the Deep Hours, and Baleful Strix. Hydroblast stays in the sideboard since this opponent has no red cards. Extract a Confession forces a sacrifice from a deck that leans on a handful of key creatures like Thorn of the Black Rose and Baleful Strix, giving us another way to break through their grindy card advantage engine. Krark-Clan Shaman and Toxin Analysis are low-impact against a removal-light control deck, so they make room for the more targeted disruption.
Spy Combo wants to assemble big green creatures off Winding Way, Lead the Stampede, and Sagu Wildling, and go over the top with Dread Return and Balustrade Spy's mill. The extra Nihil Spellbomb hampers their Dread Return flashback plan by exiling their graveyard, and Extract a Confession forces away their best threat once they've committed a big creature to the board. Cast Down is fine against their creatures but we already have plenty of ways to interact, so a couple of copies make room for the more impactful graveyard disruption. Our plan is simply to be faster: their deck is ramp-heavy with little pressure before turn four or five, so curving out with Myr Enforcer and Refurbished Familiar should close the game before they stabilize.