How do you get the Harrowing 2013 - Iceborn Keeper?
It was a mission or event reward. Riot's description in the client reads: “Earned by purchasing a mystery gift.”
Is the Harrowing 2013 - Iceborn Keeper still available?
No. Riot tied the Harrowing 2013 - Iceborn Keeper to 2013 (mission reward), and it does not normally bring back past event rewards or bundles.
