Omni-Tell wants to resolve Show and Tell into Omniscience and then chain free spells for the win, so Thoughtseize and Duress are vital to strip Show and Tell, Omniscience, or a key protection spell like Veil of Summer before they combo off, ideally on turn one or two. Collector Ouphe and Shang-Chi don't interact with their combo plan, and the extra Elf utility from Wirewood Symbiote and Quirion Ranger matters less than proactive hand disruption against a deck this explosive. Keep pressure on with the elf-ramp plan since they have very little removal, and a fast Craterhoof Behemoth or Atraxa, Grand Unifier via Natural Order can close the game before they assemble their pieces.