Greeting summoners, welcome to my build for Fiora, The Legendary French Artist. I find this build works for me in every situation. I find her fun and she is an incredible harasser.
Stats from last three games:
21/6/9
12/3/11
11/8/12

Now I'm not saying it will work for you as well as it works for me but, give it a shot you never know.

Runes, now its a mess. the reason my runes are this way is because i use this runes page for like 5 champions. So instead of changing and buying separate runes for each champion for me i use a mixture that works for every single one.

armor penetration is a must, do deal more damage.
critical strike works wonders for her.
magic resist well its useful.
attack damage i just tossed in there just for the hell of it.

These of course are the recommended masteries by phreak, i dont claim them to be my own, but it works.

I havent tried other masteries because well i find these masteries work for her. They help in damage, life steal, critical damage, health, and a little bit of magic resistance.

I go for dorans blade first for some attack damage and hp. It helps especially once you get your riposte, your attack damage is permanently increased so when you get wriggleys lantern you will automatically have that full lifesteal. Lifesteal is a must for her, it gives you the high advantage above other players. When you use burst of speed you get health back way quicker in fights. Bloodthirster for more lifesteal and attack damage. then attack speed and critical strike because believe me you wont know where their health went especially if its a squishy. you do her lunge twice and half their health is gone. Make sure to get infinity edge before blackcleaver that extra crit and damage works wonders. The black cleaver is just for more damage and attack speed.

Really I dont know how to explain why i level the way i do. it works for me, but you can level up whatever you want to level up first, i always get my lunge and burst of speed up first before my riposte because it does massive damage and i find it useful. Building one first may seem better for you but i find leveling two things first to the max helps a great deal in her case. The lunge is to do massive damage before you activate your burst of speed. Once that burst of speed comes on they wont know what happened to most of their health.

I use ignite and exhaust, ignite is when they decide they are going to run away with that little bit of health and you get uber pissed because you could of killed them. they still die if timed right. exhaust well that's for more tankier champions so you have the upper edge on them. you can use what you like but i use these because i find that they work for me better with her.

Pros:
Deals massive amount of damage.
Blade waltz makes her intargetable
Burst of speed is incredibly useful
Not as mana hungry as most champs
Strong Damage
Good Speed/Chase/Getaway
AOE Damage
Fast Jungler
Strong Ganker
Good health regain/Strong stability
Strong Shield

Cons:
Targeted first whether your fed or not.
CCs just mess up her whole world.
Blade Waltz I find isnt very useful in a 5v5 team fight unless some are close or half health. But then again it can be to because your focused first you just pop that little baby on and they have no other choice but to target other teammates which gives you a chance to get them once your ult is done. So i guess its a pro and con.
-Need a good team mate
....
thats all i can really see so far. Might update later if i find anymore cons.

As the youngest child of the noble House Laurent, Fiora always considered herself destined for greatness. The Laurents had dominated the dueling culture of Demacia's aristocracy for centuries, and Fiora's father was regarded as one of the finest swordsmen the nation had ever seen. Inspired by his tales of glory, Fiora began training as soon as she could wield a blade and quickly showed greater talent than any of her siblings. As she grew older, her self-confidence and rigid discipline only widened the gulf of expertise between Fiora and her peers. Her fellow duelists perceived her confidence as arrogance, but none could defeat her in combat, and each victory only heightened her lofty self-esteem. Even so, Fiora never allowed herself to become complacent in her training, and she drove herself ever harder to become a worthy successor to her father's legacy.

Her devotion turned out to be misplaced. On the eve of an arranged duel, Fiora's father was caught slipping a slow paralysis poison into his opponent's drink. Following the incident, many of his past opponents came forward with their own accusations: envenomed weapons, bribery, blackmail, and more. In an instant, he had destroyed his family's honorable reputation. Fiora was outraged. Not only had her hero betrayed her ideals, but Demacia's dueling elite now doubted her own ability. She desperately wanted to wipe the stain from her family's history but, even more, she wanted the world to acknowledge her mastery. She found her solution in the one arena where she could fight the world's strongest warriors without being accused of dishonesty: the League of Legends.

''Fiora's ego would be insufferable if it wasn't so . . . justified.''

-Jarvan IV