think about nerfing ?
As you can see in the change and something that still infected inside How cheat the champion first I must tell you all that I'm not crying for killing all the OP champ it just suggestion and I think if anyone can suggest more I'm not telling that what I suggest is right or must be fact just an opinion...you can tell yours
It's not about how I encounter them but how I play them it's not fun when I'm always OP with noob it's not fair when the teamwork is equal
so the nerfing make the game challenging nerf too much can destroy them but if it's fair enough(don't need to balance) the game should be really fun(when they not run from you anymore)
Let's get into the Topic
Ekko has too high damage
they say "He don't have burst down damage"
but what I've seen is "He has so damn high damage and can burst down in one combo"
where is my "Utility Assassin" ?
Also Yasuo (I play Yasuo as my main)
Double crit chance is too good for him
what about bonus damage by AS ?
or bonus crit damage ?
also his wind wall is too good
what I think is why he's too good for team
not that...he can trade nearly all fighter
what I might suggest is
Wind Barier....if you have full(ready to block)
you can use your windwall by spent it(use wind guage as a wall
it's a risky trade but paid well and fair enough
for exchange of being nerfed like this
I'd like to ask you for more HP and base damage ( Yasuo will becoming a swift assassin like Yi but better reposition on the battle field )

and even more Riven 
I think she should have less mobility
so her "Broken Wings" should be change
like Xin Zhao next 3 basic attack get bonus damage ( 3 stack of Runic blade added when use and the 3rd attack air knock in the area )
with this Xin Zhao should have buff too (slow is great for him)

Fizz must be nerf for too high damage
but can be good if his pole no longer untargetable ( most of skill disappear because it not only untargetable but invulnerable )

Lastly Ekko ulti has too much
not only Zhonya's but Heal and 1.3AP damage
too much...it's not that easy to predict, I know
but when it's all settle everything collapse
his damage should be none...but can exchange for his next basic attack have bonus magic damage scale by AP....in a little period
and should be small number
what is good and what I saw in trailor
he can use several times in the period
that mean it's maybe same as Akali's
so he can stack it up with not much CD
what I think with this trade is
lower everything down ( AP ratio is main problem ) 
bring him up with the concept that you purpose
he'll be really great, not the assassin himself
but the assassin that can support team for the win
that mean you'll have more supporter(that have assassin playstyle)
I'm a player, and I know what's best for great game
lower his potential to bring out the true power 
(Urgot still OP somehow) 