Izzet Spellementals wants to chain cheap cantrips and flash in Eddymurk Crab before landing Sunderflock, so proactive hand disruption is premium: Duress strips Opt/Sleight of Hand or Prismari Charm before they chain. Glorious Decay is flexible here: it can destroy a Ghost Vacuum, or exile a card from a graveyard and draw, which trims the instants and sorceries that make their Eddymurk Crab and Hearth Elemental cheaper. Witherbloom Charm can destroy a Ghost Vacuum, gain 5 life to blunt the clock, or sacrifice a permanent to draw two cards. Requiting Hex has no targets, since none of their creatures has mana value 2 or less. Stir Up Trouble is clunky when it needs a sacrifice or four extra mana, and Callous Inspector doesn't do enough work in the race. Keep your proactive curve intact since this matchup is largely a race you win by being faster and disrupting their engine.

Dimir Midrange's Kaito, Bane of Nightmares and Enduring Curiosity are the cards that grind you out, and Strategic Betrayal is a clean answer when they are light on creatures. It is an edict, so your opponent chooses which creature to exile, and it is best when they control only one creature, such as a lone Enduring Curiosity. Exile also sidesteps Enduring Curiosity's death trigger, so it does not come back as an enchantment. Kaito is not a creature on your turn, so Betrayal cannot hit it. Duress preemptively takes their Kaito, Requiting Hex or Bitter Triumph before it can answer your threats. Stir Up Trouble is clunky here, since it needs a sacrifice or four extra mana against a deck full of cheap removal. Thinning small bodies like Callous Inspector and one Zealot smooths the curve toward bigger impact cards. Keep Lively Dirge and Obsessive Pursuit, as they generate value to match their grindy plan.

Dimir Excruciator plays its own Duress and Requiting Hex plus card-quality creatures like Seasoned Cryomancer, so landing your own Duress early strips their interaction or removal before it can be used against you. Strategic Betrayal is an edict, so they choose which creature to exile and will give up their weakest one. Its real value here is exiling their graveyard, which shuts off Superior Spider-Man copying a creature card from it and blunts their graveyard recursion. It is best cast when they control few creatures. Stir Up Trouble is clunky removal that needs a sacrifice or an extra {4}, and the small bodies (Callous Inspector, one Umbral Collar Zealot) are weak blockers against their bigger 4/4 and 5/5 creatures. Maintain card advantage via Lively Dirge and Obsessive Pursuit to outlast their grindy, removal-heavy gameplan.