Hi, I'm a gold Elo League player and this is my first guide. Riven is my main and has been since I picked her up about a week after her initial release. She's a very versatile champion in the top lane with very few bad matchups and is an asset to almost any composition.

I believe that this is 100% the most efficient build for Riven and I hope you will take my tips on board and try it out.

Pros:
Dominant laner, ESPECIALLY at levels 3 and 6.
Snowballs very hard.
Gets tanky from AD because of Valor.
Extremely strong early and mid game making her roaming deadly.
Tough to gank because of triple hop, stun and dash.
Manaless!

Cons:
She isn't as tanky as other champions with this build - this can be quite detrimental to your team if you don't have a tanky jungler.
Quite reliant on Guardian Angel to be a TRUE terror in late(r) game team fights.
If playing against good players that can kite she is quite reliant on flash to assassinate enemy carry.
Role changes late game from a total stomper to a slightly more cautious semi-tanky assassin.

The runes I choose are pretty set in stone. Armor Seals for laning, scaling MR Glyphs for those pesky APs, and flat AD Marks and Quints for easier last hitting, a stronger shield and early game trading.

The scaling glyphs can be replaced with flat MR if you know you're laning against top lane AP (Vladimir, Rumble, Swain, etc).

Pretty ordinary masteries that give a nice mix of offense and defense. I personally prefer the single point in utility for the Flash cooldown.

Skill breakdown:

Passive: Runic Blade - Makes Riven's auto attacks stronger after an ability has been used.

Q: Broken Wings - Once activated you get 3 slashes, propelling you in the direction of your mouse slightly, with the final slash knocking an enemy champion briefly into the air. This is a good skill for chasing and the biggest reason that Riven's passive is so strong.

W: Ki Burst - A small AOE stun in the area directly around Riven. The perfect tool for trading and Riven's main source of burst damage.

E: Valor - A short dash that also gives Riven a shield. The best thing about this shield is that it scales with AD, meaning that the stronger you are the more it shields you!

R: Blade of the Exile - 15 second mad steroid, giving bonus Attack Damage, bigger range on your abilities and auto attacks, and an active skill-shot, "Wind Slash," that does execution style (the lower health they're on, the more it does) damage to any targets it passes through.

Start Q for both laning and invasions, however it is worth starting E against some matchups (I will go into that later). W provides burst damage and an on-demand stun and as such should always be maxed first. Technically Q provides more flat damage if maxed, but W provides the added utility and instant burst. I take R whenever possible and max E last, however E can be maxed before Q if you are losing to a particularly brutal lane.

Start with Boots and 4 Health Potion. After covering for your jungler go back for the 4th potion. Cloth Armor is 100% fine versus particularly difficult matchups.

Next you'll want 2 x Doran's Blade and Sight Ward for the early game lane domination, many will recommend it but I feel like you get more with the Doran's Blade than with The Brutalizer.

Depending on how much you back with next you pick up a Vampiric Scepter for the extra sustain and Mercury's Treads, although Ninja Tabi aren't a bad choice depending on team comp. and whether you just want the early armor and movement speed. Getting your B. F. Sword can be done before Vampiric Scepter with no problems.

Bloodthirster is the bread and butter of Riven. It provides AD so that you are a total monster during mid game, and the lifesteal for coming out on top in situations that seem stacked totally against you. With this item and your ultimate popped you can kill any squishy in a matter of seconds and anybody else relatively quickly as well.

Guardian Angel is what you want to grab next. The stats this item gives are nice and help to make you last a little longer when you're in the middle of those team fights; but ultimately the utility that this item gives is priceless. The second life can help to take focus off you in fights and is simply invaluable for Riven as you aren't particularly tanky. This item simply gives so much to your suicidal swath through the enemy team.

From here it gets situational: the item build I gave at the top is what I most commonly will get, however here I'll go into more detail on what can be gotten:

NOTE: THE FOLLOWING CAN BE GOTTEN IN ANY ORDER DEPENDING ON HOW YOUR PARTICULAR GAME IS PLAYING OUT.

Last Whisper if the enemy team has (they should) started to build armor and you are surviving long enough in team fights to merit the extra AD and ArPen instead of more survivability.

Hexdrinker and Maw of Malmortius if the enemy has a strong AP presence, usually in the form of a fed mid or 2 AP champions; be they top/mid/jungle in any combination. This item gives Riven some more damage, nice MR and a shield that gives her some more survivability on top of Valor and the Guardian Angel. I feel that the extra shield just works well with Riven's hectic style and team fighting role.

Randuin's Omen gives much needed armor and health to deal with the horror of late game AD carries. The active is perfect for Riven as she should be right in the middle of the enemy team, or on top of the AD carry. If short on cash and you want to get some decent armor and then concentrate on damage Warden's Mail can be bought to tide you over.

Aegis of the Legion amazing, underrated (on anyone but support) item. If your support has yet to pick this up I'd definitely consider it. Gives cheap resistances that help you survive longer and gives your team a nice aura too. Very cost efficient.

Getting a second Bloodthirster is 100% fine if you manage to get that far and feel as though you don't need the added utility of the items above.

SPECIAL NOTE:

I would NEVER get Frozen Mallet or Wriggle's Lantern on Riven. Frozen Mallet, in my opinion, does not compliment the playstyle of Riven at all. She has no problems chasing, and if you want HP you're better off with Randuin's which has a fantastic active and the added addition of armor. You want to burst the carries down as fast as possible while surviving and I feel Frozen Mallet fails to help Riven achieve this. Wriggle's Lantern delays your purchase of Bloodthirster too long. It does not give the laning domination that Doran's Blade gives and to top it off Riven does not auto attack all that much for me to recommend it - she's an AD caster with a reliance on auto attacks in between skills to make use of her passive. Not a "right click and win champion."

Laning

aa=auto-attack

You have a strong level 1 with a point in Q. Most players would be fools to try and trade with Riven at level 1, but if they do the most damage you can possibly do is Q-aa-Q-aa-Q-aa, making good use of Riven's passive. Be careful of minion aggro in the early levels. At level 2 your combo extends to Q-aa-Q-aa-W-aa-Q-aa, should you find yourself in a position to utilise it safely without the fear of taking too much damage from the minion wave.

Level 3 is the time to go hard. You have a number of options here:

If you want to trade with the enemy and know that they cannot out damage you, i.e. weak early laners Vladimir, Nasus, Irelia, etc, then you want to Q-aa-Q-aa-W-aa-Q-aa-E to chase and then repeat.

If you want some quick, low-risk harass then you E into range of the enemy, W to stun, aa, Q, and then use your final 2 Qs to get out of range before they can fully retaliate.

My general goal is to have the enemy on around 1/2 or 2/3 health for when you hit level 6. They will probably be under their tower at this point. If they are under the tower you want to go into the brush, activate R, flash on top of them, W, ignite, and either execute them with your R active or use your Q combo before the R execute and use E to tank a tower hit and get away. Hopefully you can snowball the lane with an early kill at level 3 or 6 and continue to keep your laning opponent pushed into the tower so you can either deny them farm, farm THEM, or freely roam to mid lane for kills there.

When getting ganked as Riven you have a few options, but if you're pushed pretty far up the lane abusing the brush is key. You can often turn 2v1 situations into a double kill or at the very least a single kill:

When you see the jungler enter your lane get into your brush and if possible stun both the jungler and the enemy laner just as they enter the brush. Then use your E and Qs and if necessary Flash to escape to your tower.

If you are pretty strong, or you know for a fact you can't escape - i.e. laner and jungler with strong CC and your flash is down - it is often a good idea to try and turn the gank around into a kill for yourself, or even a double kill. Run into the brush, activate your ultimate, try and get a double stun, followed by an Ignite on the most susceptible target, spam your Qs for some extra damage followed by the execute on your ultimate. I cannot count the number of times I've turned a gank into a double kill for myself.

It's also worth noting Riven is a notoriously difficult champion to tower dive - with the shield on your E, a mini-knockup and a mini-stun you'd have to be a fool to dive Riven unless you were very confident she could be killed.

Team-Fighting

In mid game team fights Riven is pretty ludicrous. She does a lot of AOE damage in amongst enemy teams and provides a mini-stun and a knockup while being pretty hard to kill. In the late game this utility drops off slightly due to her damage being significantly less after enemy resistances have been built and her dying a lot faster to damage from AD carries.

The general goal of Riven is to murder a high-priority target, usually the AD carry. If you are the intiatior on your team (you probably shouldn't be) you'll need to pop your R, Flash on top of the enemy carry, and fully combo them. If you kill them like this you'll want to either move onto another target or get out of the fight and wait for your Q and W cooldowns. As you can see Riven is a very "balls-deep" suicidal champion. This is why it is always best to fight with your Guardian Angel up.

Even if you aren't the main initiator of your team you'll stll want to try to save Flash to guarantee that you output all of your damage onto the highest priority target.

Riven Tips and Facts

Valor can be used in the laning phase to tank minion hits - you can often win trades just by shieling the minion aggro while an enemy takes full damage from minion fighters and casters.

It is usually best to try and use Valor to shield an enemies main harassing tool. However it is often worth starting with Valor versus annoying level 1 champions such as Kennen, Nidalee, Vladimir, Jayce, etc. that have ranged auto attacks. The reason for this is you want to take as little damage as possible before level 3 when you have your full combo. In these cases use Valor to tank enemy auto attacks while you go for last hits.

Amusingly if you start Valor verus Olaf you can win any early trade by shielding his E.

If you're going to all-in someone always use Ignite early as opposed to try and finish them off. The reason for this is the 5 AD it gives you from masteries.

You can use Broken Wings to hop through the thinnest part the wall at bottom lane near tri-brush. Not particularly useful but you never know!

Riven is the strongest champion in the game at level 1 if you start with a Doran's Blade, although this gimps your early laning unless you're a very very good Riven player!

A lot of Riven-hipsters run Heal Ignite, if you've read my guide you'll know by now how necessary Flash is for my Riven playstyle.

*Under Construction*

Riven is my top laner of choice and I hope you will give her a shot using my build and tips!

Please don't hesitate to leave criticism as it is my first guide and I do intend to update it, especially the matchup section.

However, while I am open to criticism, I've played 100s of games with Riven and I know that the build I have outlined is the most efficient. Although do feel free to post what you prefer to build and I'll tell you why it isn't the best way!