The best champs outside of lane to counter Jayce include Kog'Maw, Kai'Sa, and Sivir. These champions are all good at countering Jayce with decent win rates over 61%. Even if these Jayce counter picks are not chosen in the same position as you, it's not smart to choose him into these matchups. They will usually destroy Jayce.
Yet, if the opposite team choses either Naafiri or Shaco, you should seriously think about taking him, as he easily wins against these champions with win rates over 52% against both ofthem.
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