How do you get the Inkshadow Yasuo 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 Inkshadow Yasuo Border Icon still available?
Probably not. Riot tied the Inkshadow Yasuo Border Icon to 2023 (bundle), and it does not normally bring back past event rewards or bundles.
