This is a close mirror-like matchup against another tempo-oriented Phelia/Solitude deck, so Kaito, Bane of Nightmares adds a resilient hexproof threat during your turn that dodges their removal like Galvanic Discharge. Mystical Dispute is efficient at {U} against their many blue spells including Quantum Riddler, Consign to Memory, and Teferi. Prismatic Ending is less efficient against their similarly-costed threats, and Witch Enchanter has fewer relevant artifact/enchantment targets here. Keep Thoughtseize and your full removal suite to fight through their Solitude and Wrath of the Skies.