The Championship Riven icon, which was originally announced to commemorate the S2 World Championship, has been revealed at a bit of an odd time.
announcement about the S2 World Champs, you'll find a redeem link under the question "I want a Season Two Championship Riven summoner icon! How can I get one? ". This will take you to new page where you would have the option to enter a code ( similar to how Riot handled the redemption of the Gamescom badges ) and also give you a little preview of the icon.
The code to get this free icon will be broadcasted during next weekends Season Two World Championship Finals between the two teams to emerge victorious from the final day of the World Playoffs. Once they broadcast the code ( AGAIN, DURING THE FINALS NEXT WEEK ), summoners will have 24 hours to redeem it. I'll be sure to keep you updated once everything kicks into motion.