Dimir Midrange is packed with countermagic like Counterspell, Force of Negation, and Spell Snare plus efficient threats like Psychic Frog and Orcish Bowmasters, making this a disruption fight. Consign to Memory counters their Quantum Riddler and Tamiyo, Inquisitive Student triggered abilities (the draw/investigate triggers) as well as any colorless permanents they might deploy, and Mystical Dispute is cheap, efficient interaction against their many blue spells like Counterspell itself. Into the Flood Maw is weak since bouncing a Psychic Frog or Orcish Bowmasters just delays a card they can recast, and we would rather hold countermagic to protect our own combo. Keep our full complement of Force of Negation and Counterspell to fight through their control shell and resolve Goblin Charbelcher.