How do you get the Valiant Sword Riven Border Icon?
It was released during a limited-time event. Riot's description in the client reads: “This icon was acquired during the 2019 Worlds event.”
Is the Valiant Sword Riven Border Icon still available?
No. Riot tied the Valiant Sword Riven Border Icon to 2019 (limited-time event), and it does not normally bring back past event rewards or bundles.
