The greatest champions globally to counter Jayce include Kog'Maw, Kai'Sa, and Sivir. These champs are all good at countering Jayce with high win rates over 61%. Even if these Jayce counter picks are not chosen in the same position as you, it's not a good idea to take him into these matchups. They will usually crush Jayce.
Yet, if the other team choses either Naafiri or Shaco, you should strongly think about taking him, as he easily beats these champs with win rates over 52% against both ofthem.
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