How the hell do I fight Riven top?
Even if behind she just seems to be able to rofl stomp and one shot anyone. And her ult seems to do a good 1/3rd to half of your hp. I just played a game where she took ignite so I literally had to spend the first 5 minutes farming under turret so I didn't get cheesed then she could just dive me because he E let her tank turret for 3 hits and her E and Q give so much mobility. Even if I stunned her (playing Irelia) it didn't matter because she just Es and then Qs and gets away. I've literally never seen a champion without invulnerability or untargetability of some sort who can just 1v5 like her. And even if she gets cc'd it doesn't matter since she can just dodge untargeted things with her mobility or give herself an 800 hp shield and lifesteal to full hp.
Literally seeing this champion just makes me want to dodge because whenever I ask people how I can fight her they just say "just cc her" which NEVER WORKS.
These are the only ones that come to mind right off the bat.
Otherwise you're trying to be smart and not die. If you deny her kills, then she will fall off in effectiveness.