Lavinia, Azorius Renegade is excellent in this blue mirror, countering their free Force of Will and Daze when cast without mana and preventing them from casting Flow State and other noncreature spells with mana value greater than the number of lands they control. Surgical Extraction, castable for 2 life, can strip a growing Nethergoyf from their graveyard before it becomes a problem, or answer redundant copies of Thoughtseize/Fatal Push. Counterbalance is weaker against their varied low curve of one-and-two mana spells that dodge easy matching, and Back to Basics is risky since we also run nonbasics and they aren't overly reliant on tapped nonbasic lands. Keep the core Jace/Stoneforge threat package since it outclasses their clock in a grindy game.

Ocelot Pride Midrange floods the board with 1/1 and 2/1 Cat tokens; Fire Magic's Fira mode for {2}{R} (3 mana total) deals 2 damage to each creature, wiping their small creatures and tokens (Ocelot Pride, Cat Warrior tokens, Hexing Squelcher) while our bigger threats like Batterskull or Kaldra Compleat survive. Back to Basics is weak since their manabase leans on basics like Snow-Covered Plains and they don't overextend on nonbasics. Our removal suite of Swords to Plowshares and Prismatic Ending already answers their key threats like Ajani, Nacatl Pariah and Guide of Souls, so the rest of the plan stays stable.

Eldrazi's entire mainboard is colorless, making Consign to Memory a premium answer that counters Reality Smasher, Thought-Knot Seer, Eldrazi Linebreaker, Sire of Seven Deaths, and even Chalice of the Void as they're cast. Lavinia, Azorius Renegade restricts their Kozilek's Command and Eldrazi Confluence when their mana value exceeds their land count, making it harder to deploy disruption alongside their proactive threats. Spell Pierce is weak since Ancient Tomb and Eldrazi Temple give them plenty of mana to pay around it, and Back to Basics is cut because, while it stops nonbasic lands from untapping regardless of whether they produce colorless or colored mana, it does little against threats that have already resolved. Teferi and Dress Down are cut since they don't meaningfully interact with a deck of efficient colorless beaters.