“Gruul Basking Broodscale Combo is a colorless-leaning Eldrazi combo deck. The combo is Basking Broodscale equipped with Blade of the Bloodchief: sacrificing an Eldrazi Spawn token is a creature dying, so Blade puts a +1/+1 counter on Broodscale, which makes a new Spawn, which can be sacrificed again, giving unlimited colorless mana and unlimited Spawn entering the battlefield. With Glaring Fleshraker in play, each Spawn entering deals 1 damage to each opponent, so the loop kills on the spot; without Fleshraker it still produces unlimited mana and an arbitrarily large Broodscale. Urza's Saga's chapter III fetches Blade (or a one-mana artifact answer such as Vexing Bauble, Haywire Mite or Soul-Guide Lantern), and Ancient Stirrings and Malevolent Rumble dig for the missing piece. Eldrazi Temple and Ugin's Labyrinth power out Devourer of Destiny and Emrakul, the Promised End as a big-mana backup plan, and Kozilek's Command is flexible removal and card flow. The deck is weak to artifact removal on Blade, to cheap instant-speed removal on Broodscale in response to the loop, and to effects that stop tokens or sacrifice. When sideboarding, the combo pieces stay in; the flexible cuts are the expensive top end (Emrakul, Devourer of Destiny), Sowing Mycospawn and situational one-mana artifacts.”
Missing sideboard cards? The full 15-card sideboard runs about $127.
Buy sideboard on ManapoolThis mirror-adjacent matchup comes down to who assembles Broodscale plus Blade first and who can interact with the opponent's combo pieces. Dismember is premium interaction against their Basking Broodscale (a 2/2, so -5/-5 kills it even after an Adapt counter) and can also kill a Sowing Mycospawn or Haywire Mite. In this deck it costs one mana plus 4 life, since we have no black mana. Don't point it at Devourer of Destiny, which is a 6/6 and survives -5/-5, or at Emrakul, which has protection from instants. Thief of Existence can exile their Blade of the Bloodchief (mana value 1) when you cast it, which keeps it from ever growing their creatures, and it leaves a 3/4 body behind. Emrakul is a late, clunky top-end in a race decided well before turn 7-8, and Sowing Mycospawn is a slow four-mana play that does little to stop their Broodscale and Blade plan, so both are the easiest cards to give up here.
This is a mirror match, so the combo pieces and core engine stay untouched since both players are racing to assemble the same loop. Thief of Existence comes in to exile their Blade of the Bloodchief (or Vexing Bauble) on cast, which is the single biggest blow you can land against their combo. Pithing Needle can name Basking Broodscale to shut off their Adapt activation, preventing the loop from ever starting even if they have Blade equipped. The expensive top end (Emrakul, the Promised End) and the extra Sowing Mycospawn come out since this is a race to assemble and protect the combo rather than a grindy top-end fight, and those cards are too slow and clunky for the mirror.
Izzet Prowess wants to chain cheap one-mana spells (Lightning Bolt, Lava Dart, Preordain, Mutagenic Growth) and free spells (Mishra's Bauble) into Dragon's Rage Channeler and Monastery Swiftspear triggers. Trinisphere taxes all of that up to three mana, badly disrupting their curve and their ability to pay for Mutagenic Growth's Phyrexian mana or flashback Lava Dart cheaply. Damping Sphere further slows their burst turns by capping mana from tapped lands and taxing multi-spell turns. Emrakul is too slow against an aggressive clock, and the second Sowing Mycospawn is cut since ramping is less relevant than surviving the clock.