This matchup is a race against their engine, so disruption before they chain spells is key: Duress strips Prismari Charm or Traumatic Critique before it can protect a threat, and Ghost Vacuum exiles cards from their graveyard to shut off Eddymurk Crab's cost reduction and starve Flow State's upgrade condition. Strategic Betrayal is strong since it exiles both a creature (Hearth Elemental or Eddymurk Crab) and their graveyard at once, hitting two engine pieces simultaneously. Bitter Triumph comes out since it's a worse removal spell against undersized creatures compared to our sweepers and the extra disruption, and Sandman and Emeritus of Abundance are cut as they're too slow and don't interact with the opponent's plan. Keep Deadly Cover-Up in as a reset against their board of growing Elementals.

UR Aggro wants to chain cheap spells into Slickshot Show-Off and Pompous Battlemage pumps, so Duress is excellent at stripping Burst Lightning or a key payoff before it comes down. Ghost Vacuum slows Eddymurk Crab's discount and denies any graveyard-based value they pick up along the way. We trim the slowest, most reactive cards — Emeritus of Abundance and Sandman don't affect the race and Elven Passage is replaced by more interaction. Keep Deadly Cover-Up and Requiting Hex in, since both are efficient answers to their small, aggressive creatures.

Dimir Midrange relies on card advantage engines like Enduring Curiosity and Kaito, Bane of Nightmares, so we want to disrupt those while keeping cheap interaction for their small creatures. Strategic Betrayal forces them to exile a creature of their choice along with their graveyard. It is best when they have few creatures, and if the creature they pick is Enduring Curiosity, it is exiled rather than dying, so it cannot return. Duress strips their removal (Requiting Hex, Bitter Triumph) or disruption (We Say Thee Nay!) before it matters. Garruk, Veiled Butcher's exile-on-death static ability also stops Enduring Curiosity's self-recursion trigger outright. We keep our Requiting Hex in, since it cleanly kills their cheap creatures like Floodpits Drowner, Dream Beavers, and Spyglass Siren, though it cannot touch Enduring Curiosity or Kaito. The slots come from the slower cards, Elven Passage, Emeritus of Abundance, and Icetill Explorer.