Step 1 : Choose 1 of these champs listed , these slightly beat fiora if u play it atleast decently 
These champs hard counter her 
Step 2 : Rush for 
(unless your pantheon) ,(with trundle just wait till you have your ult and you always win), and(with jax all you have to do is literally dodge her w at all times)
Step 3 : after you get 1 damage item grab
or
Step 4 : beat her in 1v1
Step 5: She outscales you anyways, claps your carries, and 1 v 5's.
Also just a side note, Fiora claps GP and is decent against Jayce.
She beats kled as well
Fiora's problem is she dominates lane but even if she doesn't her damage scales so well she just dominates anyways so it doesn't matter
I can confirm as an avid Troll King player that he does not hard counter Fiora. She easily outduels him after two items and anything before that is a skill matchup (in her favor since nothing beyond Rabid Bite really helps him win trades against her, and she won't just sit there and trade autos). From what I've seen, she has no hard counters. She also split-pushes harder thanks to his Q no longer damaging structures.
Even before his nerfs, the matchup was still in her favor. Now with the longer Pillar/Subjugate cooldowns, she has the advantage nearly all of the time.
As a Level 5 Fiora main, do note that:
GP does decent against her, it's a pretty fair matchup
Jayce is a skill matchup, so is Renekton; again, a fair matchup.
Pantheon, Tryndamere, and Olaf counter her
Trundle, Kled and Jax have a disadvantage against her. If the Fiora knows what the hell she's doing, then you shouldn't be able to 'just dodge her W'.
To counter Fiora, DO NOT PICK SOMEONE WITH CC.
Mastery level 7 fiora: -she absolutely destroys gang plank. That's my favorite match up.
You can snowball the matchup early as Darius if you don't overextend. You can also snowball the matchup in the other direction if you let her get an early kill, because you'll immediately be useless for the rest of the game unless you get a huge TP play bot lane or something.
I just play illaoi.
....that's it.
The fact Fiora does MAX HEALTH % TRUE DMG means that no matter how tanky you get she will always kill you in the same amount of attacks. Only chance to beat fiora is to kill her first
