Omni-Tell wants to resolve Show and Tell into Omniscience or Emrakul, the Aeons Torn, so our removal spells like Swords to Plowshares are largely dead against noncreature enablers and come out. Force of Negation is the premium answer, letting us counter Show and Tell, Omniscience, or Stock Up for free on their turn before they can chain into a win. Lavinia, Azorius Renegade counters any spell cast without paying its mana cost off Omniscience as well as free Force of Wills, while also restricting noncreature spells with mana value greater than their land count. Teferi, Time Raveler is less relevant since Emrakul can't be countered anyway and their real risk is Show and Tell resolving, which Teferi doesn't stop, so it steps out for more free countermagic.