Whenever someone buys Dreadknight Garen

https://cdn.meme.am/instances/500x/69400237.jpg

You can get the skin for free for following Riot on Twitter

Instructions in this link

https://support.riotgames.com/hc/en-us/articles/202083184-Promotional-Content-Free-Swag-

You can also get Riot Girl Tristana!