How do you get the Empyrean Jhin Border Icon?
It came in a bundle. Riot's description in the client reads: “An icon that entitles the border for this champion”
Is the Empyrean Jhin Border Icon still available?
Probably not. Riot tied the Empyrean Jhin Border Icon to 2022 (bundle), and it does not normally bring back past event rewards or bundles.
