Ok, this is quite old but it still works. Get your free Tristana champion and the Riot Girl skin for free if you become a Facebook fan of League of Legends! I’ve noticed some people have difficulty finding the right page to like, but here are the easy “facebook connect” links for every server location.
Riot Games always have these promotional things and this time you have to sign up to their Youtube channel. As a reward you will get the champion Alistar for free, if you don’t have him yet, and the cool blue bull, Unchained Alistar skin.
Click on your server location get your free Unchained Alistar