Come check out my other guides if you either want to learn that specific champion or think this guide was information/helpful.

I think I am done with this guide and won't update this much anymore. If you have questions I don't mind answering them so go ahead and ask if you want to.
I've been playing Sivir ever since I started LoL and used her to get to level 30 and have over 100k mastery points with her. I will soon talk about masteries, item preferences, game play, pros and cons, and more. Please comment to tell me how to improve.

Why play Sivir?

You should play Sivir because she is a champion which does well during the laning phase and farms very well. She spikes up in power the moment your team starts to group with her ultimate and AoE damage which is now insane since her W's bounces can crit now. Sivir is not a hyper carry, but excels at defending base, pushing, grouping and is also a pretty safe pick with her shield. She also has one of the easiest farming kits in the game. Her kit is quite unique for an ADC and provides a good amount of utility while being forgiving enough to help your team when you fall behind.
Once again I'll say this, please feel free to comment and give me constructive criticism or suggestions or comments on grammar or clarity issues.

Pros

-Brings a lot of utility
-Has insane damage mid and late game
-Quite safe with a shield
-Insane pushing/base defending power
-Can turn fights with her shield and ultimate
-Best waveclear, maybe with the exception of Gangplank.

Cons

-Squishy (just like every ADC, but Graves).
-Not very long ranged
-Needs her items for damage
-No reliable escapes/dashes
-No crowd control

This spell is a MUST TAKE. Flash is the most versatile spell and can be used for many purposes. Almost every champion takes this the exception of several champion such as Shaco who has his own Flash ( Deceive), but even champions like Ezreal who have their own blink ( Arcane Shift) still take flash showing how good this spell is. This spell gives so much and has a lot of potential do things such as outplay, secure kills, escape, etc.

Offense

How to use flash offensively:
-Get in range of an enemy so you can Boomerang Blade or auto attack range to finish them off.

Defence

-Use it to avoid damage and run away from enemies when you are low health.
Not really an offensive spell, but it does give a short burst of movement speed, so you can use it to catch escaping enemies without shields or dashes.
You should almost always use it for defense or trading. Often people wait for their hp to get really before using it as an element of surprise to catch the enemies off guard and win a fight though this is risky against bursty champions. Remember, don't ever hesitate to use this to save an ally. If you are low but can heal from lifesteal/recall without punishment, don't use this spell to heal up randomly. Just don't waste this spell if you're going to die anyway.

Other Options:

Barrier is outclassed by Heal. Heal not only gives a sense of security to yourself, but also to your support since you can save each other. Barrier is more of a selfish spell, so just take Heal. Heal also has a nice movement speed buff for a short time unlike Barrier.


Ghost is similar to Flash. They both have very similar uses, though Flash can be used more of a surprise since Ghost is not in an instant, it can more easily be reacted to. Flash also gives a better outplay potential since you can more easily dodge skillshots.


Exhaust is like Heal for supports as a default spell. Though if your support takes Heal and you take exhaust, it won't change much during the laning phase, but will decrease your ability to survive afterwards. In my opinion, your support is better with it, but you can take it instead sometimes. Building lifesteal may compensate for your lower sustain without heal.


Sometimes your support will take this over exhaust to secure kills. Your support should only take this if they are a support which makes it a kill lane like Blitzcrank. In my opinion, you should never take this because this will make you more vulnerable. Even in a kill lane, you should just let your support take it instead.

Teleport in my opinion is not very viable as a ADC, though it brings a lot of utility and is very good to have on at least one person in your team. Smite is only for junglers, so you shouldn't be taking it. Clarity is pretty bad since you already have you Spell Shield.

We get fury since we auto attack a lot as an ADC and our main damage source is from that. Sorcery only would benefit our Boomerang Blade, so fury is better. It also allows us to farm more easily in the early game.
I personally take exposed weakness though others take feast for the sustain early. Exposed weakness is easily proced with our Ricochet and on top of that, our ultimate also boosts out allies. I think this improves our late game rather since we are our late game is our main focus.
You more damage the longer you live, common sense right? I favor this over Natural Talent because I like to live longer rather than get more damage from our poke off with Boomerang Blade. This also sustains us in lane.
2 kills gives this more value than Oppressor . You're the ADC, so you should be getting kills, Oppressor also is cc reliant, so getting it would weigh you down in 1v1s since you have no cc and not all supports have a lot of cc, so Bounty Hunter is better.
We are AD, not AP. Easy answer, mages take the other, fighters, ADCs, etc take armor penetration. No contest, you shouldn't be taking the other option.
You attack a lot. Fervor of Battle likes that. Sivir has good synergy with Fervor of Battle with her On The Hunt and Ricochet, so why not take it along with some AS items. She easily can generate sever stacks on Fervor of Battle , so this is the best choice.
ADCs don't roam...at least you shouldn't during the laning phase. As Sivir, you should be focusing on farming and not only does this help with that, but the other is useless through the laning phase. You should only leave lane when you start to group or when you got the turret and you won't lose your's when you help other lanes out.
This is the best choice, the others don't mean much to you. Runic Affinity is only good as a jungler or a mid laner which knows they'll get blue. Assassin is pretty bad since you will almost always be with your support. Secret Stash will give you more sustain. It is clearly the best choice.
You don't really go mana hungry UNLESS the enemies decide to NEVER throw out any skills at you since you have your Spell Shield which refunds mana. Even when pushing with Ricochet, you should have mana still. Merciless will improve damage, so this is better.
This is better since you'll be the one killing the minions, not your support. Good in skirmishes and fights also.

Okay, get ready for a long journey of words, preferences and opinions. If you don't want to read this, I have notes in the build above for just general and quick reading if you're in a rush/lazy or don't want to main Sivir, but play her as a counter pick rather.
Infinity Edge VS Essence Reaver
So, do you start Infinity Edge or Essence Reaver?
Infinity Edge has always been a core item on many ADCs. You should get Infinity Edge if you don't find yourself wanting to use your skills while they're on cooldown. If you are auto attacking a lot for harass and not having trouble shielding skillshots. This also builds out of pickaxe if you bought this first back.
Essence Reaver is a great item imo. I really like the cdr, but I personally rush Infinity Edge. You should get Essence Reaver if you find your lane being a poke lane and you are using your Spell Shield a lot to avoid damage though sometimes it is down and you take the damage. Also get it if you aren't having many skirmishes since this is more defensive and less damage.
Remember, if you are using my build, you will still build the other item in the end.
TLDR: Essence Reaver-Defence and getting poked a lot. Infinity Edge=More damage and more fights, you are shielding abilities well. It's a matter of preference. I like Infinity Edge better first.

First Back

This is your IDEAL first back. If you have no idea if you want to build Essence Reaver or Infinity Edge, this is perfect. The stats given are great and though costly, it is better than the others. This is amazing if ahead.
This is if you're going Essence Reaver first. Cheaper than a B. F. Sword, but the AD is significantly less. Only get this if you want to have your shield more or else get a B. F. Sword if you can afford it.
Only get this if you are going to start Infinity Edge. Vampiric Scepter is probably better if you are behind, but if it is practically even, consider to get this if affordable to build it into your Infinity Edge later rather than being put behind on items.
This item is great when behind. If you want to out sustain the enemies or stay in lane to farm longer, buy this. This will allow you to farm to the late game and catch up. I don't recommend buying this AND Cull because you'll be very far behind. Build this into a Botrk or bloodthirster later.
I REALLY like getting a Cull. Many people think the Cull sucks. I still always start Doran's blade, but often get a Cullwhen I back very soon after. Cull delays my first/second item, but allows me to get my second/third item quicker. Sivir is not an early game champion, so it's fine being delayed in the early game. Not only does this provide decent stats, it also pays for itself AND makes you earn gold. Cull is also great when behind because it gives sustain. If you hate Cull, maybe try it out once on Sivir, still don't like it? That's fine, it’s your choice on what you build.
Buy these when you have 300g leftover and don't need pots. Always get these guys at some point, I usually get them before/after Infinity Edge. Upgrade them after Infinity Edge or after Statikk Shiv/ Zeal item.
Refill your supply when backing, usually stop buying around level 10. I like having one or two at a time for sustain, but if you have a Soraka, you probably won't need them.

Now you should either have finished your Infinity Edge or Essence Reaver and got tier 1 boots. It's your time to choose now your second item and boots. Even though you have 2 feet, you can only pick one of the two boots, so make your choice of cdr or attack speed.

Why should/would you buy a cull?

In my opinion, cull is highly underrated and looked down upon by the community. I still think that you should never really start with cull because it is outclassed by doran's blade stats and sustain. However, I think this is a great item for first back especially wheb behind. While it lacks sustain, this will still give you some. Don't forget your sustain will be doran's blade and ALSO cull. This will definitely allow you to stay in lane longer and farm to the late game. Speaking of farming, that's what the cull is for. At 100 lane minions killed, you get 180 back. Cull is not for the stats, but mainly for the gold. Cull pays for itself. Think of the stats as a bonus. The cull earns you gold and allows you to get your second/third item quicker though delaying your first/second item. This is great for Sivir because she has one of the easiest farming and wave clear in the game. Not only that, but Sivir is a late game champion, she just needs to survive early and excel late, the cull encourages that significantly.
Tldr; Earns you gold and pays for itself giving you okay sustain. This allows you to get later items quicker though delaying your early ones which is fine because you are a late game champion.

When To Get Cull:
Cull is best when you are behind or have a passive support/are forced to back early in my opinion. I'll go through each scenario separately. I dislike Cull when ahead, because it allows the enemies to catch up quicker. When behind, cull is great because it allows you to catch up on items while giving you sustain. If you have a passive support, you generally stay in lane longer and farm more. This will make your lane a farming lane which is what Sivir excels at. Sivir usually will outfarm anyone since her kit is perfect for farming. Cull will give you a huge lead with the passive since you already should be outfarming them. When you are forced to back early, you have not many options to buy besides long swords, Doran's Blade, Dagger, boots and Cull. Since its still early, Cull's sustain is pretty good. It will allow you to get those later items quickly and you can just play passively and farm. Just keeping on par with cs with Cull will give you a lead, but ourfarming them will give an even bigger lead. Sivir will probably outfarm since her kit is so good at doing just that.

In my honest opinion, I personally think Cull should ONLY be bought on late game champions who can farm but never as a starter item. Late game item reliant champions should buy cull and try to farm until then and use their late power to win the game. Champions who have trouble farming should not get this because it's passive won't be of too much help. Rather champions with good wave clear should buy it because it is heavily reliant on farm. An example of someone who should buy Cull in my opinion is Gangplank since he fits all the criteria stated above or Kog'Maw since he is item reliant and the 3 life on hit works great with his Bio arcane barrage.

So, how do I usually play Sivir?

Let me break down how I play this champion into three parts: Early, Mid and Late game.

Early Game

Early Game:
Generally I just want to farm throughout the early game. Of course with the exceptions of when you have your jungler come. Generally I try to push the waves so that there is more bottom side pressure which also gives us time to do gromp if we want or potentially dragon. If we do dragon and their bot lane comes, they will probably miss half to a full wave of cs giving you a lead. If behind on cs/kills, just buy a Cull and farm back into the game. If you hate cull, buy a Vampiric Scepter if being poked.
Advantages of pushing with Sivir:
-You generally will still get all the cs since your Ricochet and Boomerang Blade make it really easy to cs.
*Generally you would naturally push the wave with Ricochet anyway.
*Your Spell Shield allows you to push even more since you can get mana for abilities to push back.
-More map pressure
*Pushing gives you the ability to either do gromp for more gold/exp; pressure dragon forcing the ADC to miss cs if they come or have 2v3 if their support and jungle come; you can also back more easily if they can't push back and have an item advantage which is when you don't push and you zone them or force them to back and miss cs.
-You probably will outfarm them
*Farming under tower is always more difficult then outside of tower. This can often lead to free poke on them with your Boomerang Blade or them using mana to cs and giving you a lead in trading if necessary.
-When you use your abilities to push, you also harass them if they dare to stand near the wave.
*Your Ricochet will bounce onto them for free damage from very far away. You can just walk away or spell shield if they try to retaliate.
*You can aim your Boomerang Blade to hit the enemies through or beside the wave for damage. If hitting from beside the wave for more damage, you can quickly walk back in front of the wave for the return to hit the wave.
-It is also hard for the enemy ADC to recover and push the wave back when you decide to back and shop.
Cons of Pushing:
- You are more vulnerable to ganks.
* If you have map awareness and a support with a Sightstone/ pink ward you should be fine.
-Your jungler can not gank.
* Unless you dive, but its dangerous in the early game so I wouldn't recommend it.
* There is a potential to gank if you back/ do gromp and their ADC is pushing the wave. Ganks generally will lead to a kill since you have a team fighting ultimate(on the hunt) and your jungler can catch up quickly. You could not push instead and use this to your advantage.
Tldr; Pushing the wave will lead to many advantages and is easy to do with Sivir. You have to ward to be safe though and be confident in your farming abilities. You probably won't get counter pushed when in lane. You have to be careful of ganks, your jungler also can't gank when your lane is pushed. Your main focus is farming.
Mid Game:
You should probably be almost halfway through your build at the beginning of mid game. Help out other lanes to get down outer turrets if not down. You should let your lane get pushed if your first tower is down and then tell your team you're backing when the huge wave gets near to gromp and push lane, but don't overextend without vision. One advantage Sivir has is her amazing waveclear. You won't take long to push or clear waves at all. The enemy ADC probably can't say the same. You can often force a 4v5 when they have their ADC go bot to clear the wave. Your On The Hunt will not only have huge teamfight impact along with your AoE damage, but it also allows your team to close a gap to force a fight. Make sure to also focus on objectives like rift herald or dragon and ALWAYS have vision on dragon even if YOU have to buy a pink ward. If you want, you could split push as Sivir if you're team is strong enough to 4v5 or hold towers. How I split push is that I buy a blue trinket and ward their jungle to be able to see if they come to flank me. I use ricochet and boomerang blade to one shot waves and if I have enough minions and no one is near, I will use on the hunt to take down the tower. Something people don't always know is that your ultimate does bot only buff you and your allies in range, but your minions too. Don't be afraid to burn this if someone comes if you can escape. However, I don't recommend split pushing since you are great in teamfights with just your ultimate and you lack reliable escapes. In my opinion, at the end of mid game/late game is when you are strongest and should be trying to pick team fights.
Tldr; Group up and take objectives. Team fights are good for you with your ultimate and AoE damage.
Late Game:
This is your time to shine when trying to team fight. You will have tons of damage for everyone on their team when just attacking one person with your Ricochet. Your Boomerang Blade will make any squishies who dare to take both the initial hit and the return cry. Your Ricochet crits with Infinity Edge will be too much for them to handle while practically never being on cooldown. If they try to cc you, you will just Spell Shield it off and continue to kill them. I haven't even mentioned your on the hunt which not only turns tables but crushes anyone trying to run away. If somehow your team is terribly behind, you can easily defend inhibitor turrets with you amazing waveclear. If something wrong happens and you are caught out alone, you can just pop your ultimate and escape if you have vision and map awareness. Your ideal late game is to group up and fight while taking things like baron and inhibitors with ease from your waveclear.
Tldr; You should be really strong here and able to do tons of damage in team fights with good positioning and shielding. If behind, you can clear waves super quick and easily to help carch up.