Consign to Memory counters their Phelia attack trigger and Solitude/Quantum Riddler enter-the-battlefield triggers, disrupting their value engine before it snowballs, and also answers any colorless spells. Mystical Dispute is efficient against their many blue spells (Consign to Memory, Spell Snare, Teferi's static ability isn't targetable but the spell itself is blue) and doubles as generic countermagic for {2}{U}. Their own Quantum Riddler and Consign to Memory mean the mirror-image matchup rewards proactive disruption over our redundant Quantum Riddlers, which get outclassed on rate by their Solitude and removal suite. Keep Thoughtseize and Fatal Push as premium interaction to strip Ragavan or Teferi, Time Raveler before it locks out your instant-speed plays.