Esper Control is almost entirely blue and white spells, so Mystical Dispute is very efficient, costing only {U} against their Teferi, Time Raveler, Narset, Parter of Veils, Day's Undoing, and countermagic. Spell Snare is weak since their key spells mostly cost one or three mana, so trim it for the more impactful Dispute. Flow State adds card selection to help rebuild after a Supreme Verdict and grind through their card advantage like Jace, the Mind Sculptor and Consult the Star Charts, so swapping it in for a single Expressive Iteration is a small change. Keep Counterspell, Force of Negation, and Murktide Regent as the core plan to fight through countermagic and close the game before Day's Undoing refills their hand with seven fresh cards. Be aware that Day's Undoing also shuffles your graveyard into your library, which sets back Murktide Regent's delve and Dragon's Rage Channeler's delirium.