How do you get the LCS 2013 - Team Coast?
It was sold in the League of Legends store. Riot's description in the client reads: “This icon was released in the store for purchase during the 2013 esports season.”
Is the LCS 2013 - Team Coast still available?
Probably not. Riot tied the LCS 2013 - Team Coast to 2013 (store purchase), and it does not normally bring back past event rewards or bundles.
