Consign to Memory is the bring-in here. Most of their threats and payoffs are colorless: Emrakul, the Promised End, Devourer of Destiny, Kozilek's Command, and the devoid Basking Broodscale and Sowing Mycospawn. All of those are colorless spells, and Consign can also counter triggered abilities such as the cast triggers on Emrakul and Mycospawn. Be aware that their green spells like Ancient Stirrings and Malevolent Rumble, and the black Dismember, are not colorless, so Consign can't hit them. Tormod's Crypt is a modest inclusion. Their deck doesn't rely heavily on the graveyard, but Malevolent Rumble fills it, and Emrakul gets cheaper for each card type in their graveyard. Shifting Woodland also needs four card types there for its delirium ability, so exiling it can slow both. Mutagenic Growth and Violent Urge are too cute against a deck that can just cast Dismember or block profitably with big Eldrazi, so they come out for more impactful cards. Keep pressuring early before Emrakul, the Promised End or Devourer of Destiny come down, since our clock is faster than their ramp-based colorless engine.

Meltdown at X=1 blows up Blade of the Bloodchief and one-mana artifacts like Vexing Bauble, Haywire Mite, Soul-Guide Lantern, and Springleaf Drum, and it also destroys any Construct tokens that Urza's Saga makes. Keep in mind it hits our own artifacts too, so Mishra's Bauble goes at X=1 and Cori-Steel Cutter at X=2. Unholy Heat is premium removal on Basking Broodscale itself (2 damage kills it before it adapts, or 6 once we have delirium) and also answers Glaring Fleshraker before it can generate Eldrazi Spawn. Cut the combat tricks since they do nothing against a combo deck that isn't fighting us on board; the goal is to either race before the loop assembles or disrupt a piece of it. Prioritize killing Broodscale on sight since it's the lynchpin of the entire combo.

This is the full mirror, so the plan is to be slightly better at removal and countering their key threats. Unholy Heat kills their Dragon's Rage Channeler or Monastery Swiftspear cleanly and can scale to 6 damage once delirium is online for Slickshot Show-Off. Mystical Dispute is cheap (often just {U}) against their blue spells like Expressive Iteration or Consign to Memory, and can also stop their Cori-Steel Cutter. Mutagenic Growth and one Violent Urge are the weakest cards here since both decks race on the same axis and we want more removal/interaction rather than combat tricks that do nothing to their board. Watch for their Consign to Memory on our colorless Mishra's Bauble and Cori-Steel Cutter tokens.