Omni-Tell wins by resolving Show and Tell into Omniscience or a giant reanimation-style threat, so Force of Negation is critical to counter Show and Tell or Omniscience for free on their turn. Consign to Memory counters colorless spells and triggered abilities, hitting relevant colorless permanents they might deploy, and is a fine flex slot given its low mana cost lets you hold up other interaction. Trim Mishra's Bauble and Into the Flood Maw since proactive card selection matters less than having answers ready for their combo turn. Race aggressively with Dragon's Rage Channeler and Cori-Steel Cutter while holding countermagic for Show and Tell.