This is the mirror match against another Gruul Broodscale Combo deck, so it comes down to who assembles Eldrazi Temple/Urza's Saga into a threat first and who has the better disruption. Nature's Claim answers their Vexing Bauble or a resolved Blade of the Bloodchief cheaply, while Grafdigger's Cage disrupts their own Malevolent Rumble/graveyard recursion plans and can be very strong if you land it before they do. Since they're likely to bring in similar Trinisphere and Thief of Existence effects, prioritize speed and proactive threats over trying to out-grind them. Keep Unholy Heat and Walking Ballista in as flexible interaction against their Basking Broodscale and Glaring Fleshraker.
Izzet Prowess is a fast aggressive deck full of one-toughness threats like Dragon's Rage Channeler and Monastery Swiftspear, making Firespout an excellent Sorcery-speed sweeper that can wipe their whole board for one mana with Grove of the Burnwillows or Stomping Ground. The extra Unholy Heat is efficient, cheap removal that answers their early plays before Cori-Steel Cutter or Expressive Iteration takes over. Cut the slow artifact utility pieces that don't affect the board fast enough against this clock. Be aware they'll bring in Consign to Memory and extra Unholy Heat of their own, so try to play your threats in ways that punish a missed counterspell.
Affinity relies on Urza's Saga and cheap artifact synergies to assemble a fast Kappa Cannoneer kill, so Damping Sphere severely slows their mana and caps their artifact-fueled draws. Vexing Bauble shuts off their one-mana interaction like Metallic Rebuke and Galvanic Blast before it resolves, and Grafdigger's Cage keeps their Emry, Lurker of the Loch plan in check if they bring it in. This matchup is a race, so prioritize Urza's Saga and Eldrazi Temple starts to pressure them before Kappa Cannoneer comes online. Trim the redundant artifact-based utility pieces that are too slow here.
Suggested new sideboard cards to pick up for the current metagame.
Missing sideboard cards? The full 15-card sideboard runs about $174.
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