Hi and welcome to my guide about Riven, imo the strongest 1vs1 champ in-game.
I play her quite long now, and i think i should be able to tell you how to play her as a killing machine!

You will see i use quite defensive runes. Why? It's essy. Riven is perfect for solo top. 1vs1 or 1vs2 should be no problem with her, especially with these runes. I prefer ArPen over Damage because if you test both, there's quite a huge difference inbetween. Of course you can chose Damage runes, but you should change at least 1 item to get some Armour Penetration ;)

I prefer offensive masteries with a little defensive touch, especially for playing solo top ;)
imo the most important mastery, which you should ALWAYS take with Riven, is Weapon Expertise, what gives you 10 % Armour Penetration. Sounds like a litte, but together with your Runes and Sunder this is Mind blowing!

R>Q>E>W
Why?
Well, 6,11,16, of course, skill ultimate. Q is the only "real" spell which does damange.
Your E Absorbs Damage and grants us a little flash, skill it for less CD and more Absorbing power! W Gives us a nice stun (0.75 sec.) Quite nice, but i would skill it as 3rd because i thing Q and E are more important and you will use them more often (Especially to escape!)

You see. ~200 armour, ~100 Magic Resist and a very nice bunch of buffs.
Ionian Boots of Lucidity
-> We got enought Resists and don't play Carry Style, so these boots are Just PERFECT for Riven!

Rush to Hexdrinker, since the update cheaper and it has got a very nice "lvl-up", but upgrade it at last!

The Bloodthirster
-> a Must-have with Riven. AD and Lifesteal, THAT's what a heavy 1vs1 champion needs!

Phage / Frozen Mallet
-> Extremly good for chasing these Garens or Mundos. Grants us a bit Damage, a very nice bunch of life and a GREAT auto-CC.

Randuim's Omen
-> Makes us a REAL tanky killer-machine. Life, Armour, a little bit CDR and this nice passive against these Tryn's who try to kill you with his ultimate and want to escape after that. This
little thing makes this impossible :)

Atma's Impaler
-> Some Armour, ~60 AD, some crit. Makes us MORE tanky, gives us MORE Damage. For ~2400 a GREAT item!

!Coming!

That's all folks! I hope you enjoy this guide! Any questions, ideas? Just message me or leave a comment! :)