I think Riven needs some minor kit adjusments
I want to clarify that I don't think Rivens kit is broken or op, like some people seem to imply. However, I do think that some parts of her kit need tweaking, because right now there are some areas that I find to be unfun in certain ways. These are mainly centered around the spamability of her spells. Now, I realize that that is where ALL her power comes from, as none of her spells are particuarly great by themselves, and also where her skill expression lies. But, as a counter to that, I find that her spells are almost so spamable that riven players are not really punished for using their spells like mad, even when it's just for no real purpose.
The main reason for this is that cooldown reduction is easier than ever to get, and get very early. You can easily have 45% cdr by level 10 even on a normal, non-snowball game, which is a fact a champion like Riven can absolutely abuse, and I think therefore should be fixed accordingly, without necessarily nerfing her to the ground.
There are a few main points I have that are more suggestions than anything, and Idk if we should introduce all of them, some of them or maybe none of them. Maybe I'm just an idiot.
My first suggestion is concerning her q. Right now, her q is easy damage, quick gap closer, quckier map movement and general mobility. I think this is too much for such a basic ability that is easy to use and, most importantly, has such a low cooldown. I don't think the ability being able to do all these things is bad in of itself, I think it's a problem that it's able to do all of them without any thought to them, so to speak. So my proposal would be this:
Increase it's cooldown at all levels. BUT, in return, give it an effect that reduces it's cooldown by an amount when it hits a minion that amounts to a bit longer than what it's currently at, and more when it hits an enemy champion so that it's cooldown ends up equal to what it is now (up to a max, so that it doesn't like reset instantly on a massive minion wave or something). Doing this wouldn't nerf it's damage in combat what so ever, since it's most likely will a champion, but it will nerf it's the ability to travel the map quickly, as well as gap close. This way, Riven can't just infinitely spam her q to gap close to pretty much any ranged champion without any chance of kiting, and neither can she use it to dodge abilities quite as much. And, if she does decide to use it that way, she'll have to CHOOSE to do that over choosing to use it for damage, which is something that tests her skill.
Secondly would be to reduce the duration of her E to one second, but in turn increase it's power. Right now, at level 5, with 45% cdr, it almost has a 3 sec cooldown, with a 1.5-second duration, meaning that you only actually have 1.5 seconds to damage her. That is, quite frankly, insane, considering that it's purpose is not to be used for long term survival, but to block super important, big abilities, like Garen's R, och or Jhin's fourth bullet. Right now, it's not being used for that. Right now, it's pretty much just spammed on cooldown to constantly block damage. It's not really a fun thing to play against, as it's almost impossible to get in damage, and the riven player isn't really punished for making a mistake since it's such a short window of opportunity.
To mend this problem, simply reduce it's duration, to 1 second, or maybe even 0.5 seconds. But, in turn, increase it's power massively. It should be used to block big spells, and if a riven player does that, she should be rewarded by blocking that entire spell. If she fails, she should be punished by a long down time. If you think this is too drastic a nerf, then perhaps we could add another effect where if her shield blocks a certain amount of damage, it's cooldown is reduced. So, let's say she uses it too block a big garen ulti, shielding 600 damage. Blocking that high amount of damage is the shields purpose, so not only is she rewarded with blocking all the damage, but the shields cooldown is reduced by 2 seconds, reducing it to a 1 sec cooldown, again making it comparable to her current cooldown.
Tl;Dr; I think right now, Rivens short cooldowns allow her to get away with gameplay that she shouldn't be able too, as well as make it very unfun for the opponnets playing against her, now that cdr is so easy to get. I think modifying her abilities to reward aggressive gameplay but punish her for using her abilities nilly-willy or incorrectly should punish her more.