How do you get the Riot 10-Year Anniversary Icon?
It was a mission or event reward. Riot's description in the client reads: “Earned by playing a game during the Riot 10-Year Anniversary event.”
Is the Riot 10-Year Anniversary Icon still available?
No. Riot tied the Riot 10-Year Anniversary Icon to 2016 (mission reward), and it does not normally bring back past event rewards or bundles.
