Quest for Warden Sivir

I have always prided myself as a force for Order and Stability on the Summoner's Rift. In my quest to ensure that my League of Legends games are both enjoyable and respectful, I sought to purchase the Warden Sivir skin for 750 RP. It would be the perfect symbol to denote my own personal Code of Order.

However, upon reviewing my current available RP; I was dismayed to find that I only possess 738. Which is exactly 12 short of the required denomination. Now ordinarily, this would require the purchase of additional RP. Something I have happily done in the past. However, while the Code is of the utmost importance to me, like Sivir I am also a fiscally shrewd man. Especially when the difference is so small.

So I beseech thee Riot, is there not some task I could perform to earn the 12 RP I require to purchase the latest in a long line of your excellent skins?