Yasuo finally confronts riven and they battle. Yasuo yells at her for killing his master, and riven, confused, says that she didn't kill him. The 2 exiled pair travel together to find the real killer....
An unreleased champion.
Calling it now.
What is it was just some guy building a 
?
Nope, riven did it.
Riven is the ony swordsman/swordswoman who weilds a wind attack from her sword. AKA rivens ulti. Which is why when yasuo plays into her he says that.
"Which weighs more, Riven? Your blade, or your past?" "Everyone faces a reckoning, Riven." "You can't run from yourself, Riven... I've tried." "Broken sword. Broken spirit." "Wait, that technique... huh." "Huh, three swift strikes..." When an enemy Riven Riven uses Wind Slash.png Wind Slash "Another wind blade?" "Who taught you that?"
There is alot of qutes there. I'm sure riven did it.
It would be an incredibly dumb bait and switch if it was anyone but Riven with how extremely hard it's been foreshadowed.
I know who actually killed the Elder: 
In fact, they also killed 
and the father of 
Here is a better story.
Riven killed Yasuo's master, because Riven is Yasuo's father.
