Hi, i play Riven since Season 3 and i thought it would be cool to make a guide for you guys!
I'm currently Diamond 5 on Brazil (eNi Pinkman), and i was Master Tier on Season 4 ending, and Diamond 1 on Season 5 ending. Well, let's do this! My english is bad so i should fail at some parts.
Before you start, this guide is based on MY perspective, so if i find for example Pantheon matchup horrible, you may think its easy, but not for me.
There's 2 item builds now! I finally updated it to Season 6.
The vs. Tanks and the vs. Squishes.
Note yourself that you don't need always to do the vs. Tanks build vs. Renekton, you could just go full AD and isntagib their carries! It's up to you.

Don't forget to read the NOTES! Those are really important and helpful.

This is the rune page i currently use, different from the build.
The one from the build is 5% flat and 5% scaling.
This one is 7,5% flat and 5% scaling (i'm sacrificing 2,5% CDR for earlier cdr)
With my runebuild i'm able to have 45% CDR lvl 9 easily, using this math:

7,5% flat + 2,5% scaling (i'm level 9 so it gives around 2,43% cdr) + 5% masteries (if running thunderlords) + youmuu's ghost blade (10%) + black cleaver (20%) = 45% CDR Level 9

Well it might be a waste for some Riven mains, i'm pretty used to this one, i kinda love it.
If you dont like this runepage, just switch the CDR quint for a AD quint.

NOTE: Grasp of the Undying is more likely a "tankier build"
(Titanic Hydra, Deadman's Plate, Sterak's, BC etc.)
This is a soon to be added build on the guide, but not now, i need to test it more.

Riven

PRO
- Insanely high damage
- High mobility
- Can be built either Assassin or Bruiser
- Fast cooldowns if built correctly
- Push lanes using Broken Wings rapidly
- Fun to play/Play maker!

CON
- Cooldown dependent
- Highly countered by CC
- Low natural sustain
- May be useless without flash on poke fights
- Depending on playstyle could be dependent on Flash

Well, this is going to be a mess!
Many good combos of Riven requires animation canceling, i'm going to put some basic ones!
Maybe i'll have some vids added later.
REMEMBER!!! NEVER USE ALL Broken Wings WITHOUT USING BASIC ATTACKS!!! Runic Blade NEEDS TO BE USED FREQUENTLY TO Riven WORK AS BROKEN AS POSSIBLE.
Also this section is currently not updated, those combos are kinda outdated, but they still work, i'm updating it asap to my newest combos.

Before we start, AA means Auto-attack (basic attack)

Normal Trading Combo
Broken Wings - AA - Broken Wings - AA - Broken Wings - AA - Ki Burst - AA

Normal Trading Combo (Ultimate)
Valor and Blade of the Exile together + Broken Wings - AA - Broken Wings - AA - Broken Wings - AA - Ki Burst - Wind Slash

Burst Combo
Valor and Blade of the Exile together + Broken Wings + Ki Burst + AA + Wind Slash and Broken Wings together
Not dead yet? Broken Wings + AA

Flash Burst Combo (Most likely late game with Ki Burst Level 5 or fed)
Charge 2 Broken Wings, save the third, Valor and Blade of the Exile together + Flash + Broken Wings + Ki Burst + AA + Wind Slash + Ravenous Hydra

The choice is between Teleport and Ignite, because Flash is a 100% pick for Riven. You should choose Ignite if you're not used to Teleport, if you do like Teleport then get Teleport and get some tps on botlane/team fights!

I dont even know why i made this chapter, because farming with Riven is quite easy.
Farming minions with Riven is most likely stacking Runic Blade or spamming Broken Wings, don't forget your Ravenous Hydra. Try to use Valor to tank possible enemy harass while farming and i think you're good to go! Don't go for suicidal farms, those farms that a Lissandra will ult you and burst you down.

Well, for now the guide is over!
Leave some comments for what you would like to see on this guide, i'll try to update her frequently!

Also thanks to /u/Guynecologist, /u/MyAccW***hadowbanned and /u/MushIsQT for the help on the guide!