The final champion for Cosmic Creation, Riven, has also been the most challenging to theorycraft for. While she obviously has great vanilla stats and some great potential, the fact that she isn't constrained also makes it much more difficult to predict how to best build around her.
Riven Reforges whenever Rally is gained, including from the Scout attack. While this has prompted many players to try to squeeze her into existing proven scout decks, RuneterraDecks built a deck from the ground up featuring Katarina and Greathorn Companion.
Many people have been making versions of Riven + Taric since Reforging generates so many cheap spells. While it's tempting to go all-in with Out Of The Way, we like NicMakesPlays' less greedy version that features Kato The Arm to just try to end the game early.
Another potential synergy is with Lee Sin since Reforging generates so many cheap spells. Here is BruisedByGod's take.
Iannogueira decided to build around the familiar Lucian + Senna, Sentinel of Light + Cithria the Bold Demacia frame.
Finally, we have this deck from user CursedParrot which looks to partner Riven with Garen. While Garen isn't always the most glamorous champ, he's also fairly easy to level up and there is some great synergy with his free rallies and Riven's passive ability.
Add Your Decks to Our Database
That will do it for Riven decks. Are there any Riven partnerships you're anxious to try out? You can theorycraft your own decks with our deckbuilder and save them to the site to share with others by logging in or creating an account.
If you see anything cool in the deck database, give it an upvote so others can find awesome creations.