When playing Riven I would recommend soloing top or jungling. She excellent in both fields and can carry a team and get you out of elo hell. When my guide says stack tiamats im serious, once you try it you'll love it. I recommend ionian boots to minimize cool down time and a wriggles lantern for it's life steal and wards that it gives wich can be a huge benefit when soloing top. Form there you can add items as they fit against the enemy team, like a blood thirster, spirit visage, or frozen mallet. I hope you enjoy my guide and give it a rating if you have the time. Thanks

-Liam