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Yasuo Build Guide by

Yasuo's Feeling Lucky (100% Crit Build)

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4 Comments League of Legends Build Guide Author xgbox

Yasuo Build Guide By Updated on

Guide Discussion (4) More Yasuo Guides

Spells:

Ignite

Flash

Items

Aggressive Start

Sustained Start

Trinket

First Back Options

Rush

Boot Options

For 100% Crit

Aggressive Options

vs AD

vs AP

vs Lots of CC

Going HAM

Final Build Example

Ability Order

Yasuo Passive Ability

Introduction

Hello! I am xGBox, and I have been playing League of Legends since 2011. Welcome to my guide on , where I will attempt to explain how I play him. I hope that this guide will provide a bit of food for thought on my playstyle of this unique champion.

There are some points I want to address that best describes the differences between other Yasuo guides:

Since Yasuo grants double critical chance from all sources, this guide suggests running some highly unconventional runes to maximize the effects of this passive. By doing will grant him roughly 10% critical chance from only five marks and one seal. See the chapter on Runes for a better breakdown.
While most AD carry champions and builds generally opt for consistent damage in the beginning and take their chances with critical strikes in the late game, this guide is the reverse. Instead, taking a small hit in attack damage allows Yasuo to reach 100% much more quickly than any other champion.
At 6300g consisting of only Statikk Shiv and Infinity Edge, reaching 100% crit at around 25 minutes is not uncommon. At this point, at around level 13, Yasuo starts to deal around 400 physical damage and 250 magic damage.
Aside from the above, I also absolutely encourage deviating from the build order. In the following chapters, I attempt to justify the items, runes, masteries, and spells that I chose, why I favor them over others, and why some options would seem viable but really aren't. That being said, the information provided is merely so you can make informed decisions.

If this sounds interesting, continue on!

Pros / Cons

Pros

High skill cap - The difference between a novice Yasuo player and a veteran Yasuo player is night and day. Good players have the capability to negate large sources of damage and utilize his fast mobility to poke and initiate fights, while new players will initially treat him as another melee carry like Master Yi.
Manaless - Like Riven and Garen, Yasuo doesn't require any resources to cast his abilities. This allows him to spam them, even on minions, without much repercussion.
High mobility - One of his low-cooldown abilities allow him to dash through enemy units, which can allow him to dodge various skill shots. It can also be used to escape from and close in on enemy champions.
Jungle traversal - Yasuo can dash through neutral monsters to quickly move throughout the jungle, similar to Lee Sin.
Wind Wall - This has the potential to be so good that it deserves its own point. This instant-cast ability can block ranged projectiles and even cancel out a vast majority of ultimates when used correctly.

Cons

High skill floor - It's going to take a bit of time to understand how to effectively use Yasuo's abilities.
Weak versus instant crowd control - Champions such as Fiddlesticks and Malzahar can easily stop Yasuo's engagements due to their targeted stuns and suppressions. He is more likely to lose a fight against a champion that have these forms of crowd control.
Needs quick reflexes - His ultimate only has a very small window where it can be cast, usually averaging about two seconds. Summoners must be able to quickly assess situations and decide whether or not to jump in. This is equally as important when using his other abilities to block projectiles or evade skill shots.
Team reliant - His ultimate requires enemies to be "airborne" before it can be cast. While he can cause that effect himself, the amount of opportunities that he can cast it is diminished for every friendly champion that doesn't have airborne effects.
Unreliable escapes - Yasuo has the potential to make some pretty interesting retreats, but they are highly dependent on the presence of enemy units and neutral monsters.

Abilities

You can read my descriptions or you can watch the Yasuo Champion Spotlight, or both. I have annotated some technical information that may be of interest to new and existing Yasuo players.

Passive: Way of the Wanderer

Yasuo actually has two parts to his passive.

Intent: Yasuo's critical chance is doubled from all sources with the caveat that his critical damage is reduced to 180% (normally 200%).

Note that while the description states 10%, it is referring to the damage dealt before it is doubled from a critical. Calculate Yasuo's critical damage as if it was a normal 200% critical strike. Afterwards, multiply that by 0.9.

The formula is:
((base) * 2) * 0.9 = Yasuo's critical damage
(200AD * 2) * 0.9 = 360 physical damage, or 180%

With :
((base) * 2.5) * 0.9 = Yasuo's critical damage
(200AD * 2.5) 0.9 = 450 physical damage, or 225%

Resolve: Whenever Yasuo moves, he charges his Flow bar. When it is filled, he gains a shield equivalent to the amount of flow. Upon taking damage from a champion or neutral monster, the shield will activate for two seconds. Afterwards, if not already depleted, Yasuo loses all his Flow.

The shield will not trigger from lane minions and turrets. The maximum Flow you can hold increases per level, to a maximum of 650 at level 18.

Note that movement traveled by Yasuo's other abilities, and will generate Flow as well, along with some crowd control effects such as the pushback from 's . can also gain Flow, but the possibility of a scenario where using it as a means to generate Flow such that it'll trigger the shield and save your life is pretty damn low, so don't do that.

Q: Steel Tempest

Yasuo's skillshot attack and primary ability works by dealing damage in a straight line. If you successfully deal damage with Steel Tempest twice, casting the third will also create a whirlwind with almost twice the range, dealing damage and sending enemies airborne.

When used while dashing with , will instead deal damage in a circle. This is also true on the third successful cast, but it will knock them airborne as well.

Note that this applies on-hit effects and can critically strike, though at around 150% total damage. Considering the base damage from the ability, this is on par to what a normal basic critical strike from Yasuo would be. The critical strike is also determined per individual unit, not on cast.

Steel Tempest's cooldown is not affected by cooldown reduction, but from attack speed. Its cooldown is reduced by 1.72% for every %1 of additional attack speed. Since every Yasuo gains +3.5% attack speed per level, at level 18 he only needs a total of +55% attack speed from other sources to achieve the lowest cooldown of 1.33 seconds.

W: Wind Wall

This is also a two-part ability.

Passive: You now gain Flow at rates of 4%/8%/12%/16%/20% depending on rank. Refer to the Passive section under Resolve for more information on Flow.

Basically, it means you have a shield available more often.

Active: This instant-cast ability will intercept and block all projectiles passing through it for 3.75 seconds. Leveling this ability increases its length and reduces its cooldown by 2 seconds each time. Refer to this list to see what Wind Wall can block (it's a lot!).

Wind Wall is more easily applied at narrow paths, such as the jungle.

Wind Wall also grants vision. It's not as good as a stealth ward, and it's not recommended to use it solely for vision, but know that it can be used in conjunction with to dash through units when a ward isn't available.

It's essentially like 's , in that it can intercept enemy abilities, but this is much better because:

It can be used to defend the entire team.
It also intercepts most ranged auto attacks as well.

This is definitely one of the most difficult skills for new players to master, but can be game changing once you understand when and where to apply it.

E: Sweeping Blade

This is a targeted ability that allows Yasuo to dash through an enemy. Since the travel distance is fixed, he can use it on an enemy from far way as a gap closer. Alternatively, you can use it on an enemy from close by as a means to escape.

Despite its extremely low cooldown of 0.5 seconds at rank 1, Sweeping Blade cannot be used on the same enemy for up to 10 seconds. Each rank decreases its cooldown by 0.1 seconds and mark by 1 second.

When trying to maximize damage, let Yasuo chain dash to three other enemies first before attacking his intended targets. This is good to utilize at the early levels because he can deal 140 magic damage to his opponent instead of 70. As the game progresses, the combo starts having less impact in comparison to his basic attacks, so it is then mainly used for positional purposes.

Dashing with Sweeping Blade will modify the effects of . See section Q for more information.

R: Last Breath

Yasuo's ultimate is an auto-targeted ability that's best described as, well, a dunk, similar to 's . When available, Yasuo will teleport to the nearest airborne champion and suspend that person, along with any other airborne champions near him, in midair for 1 second. He then proceeds to deal physical damage to all of them. Afterwards, he gains 50% armor penetration to bonus armor for 15 seconds.

Bonus armor refers to armor granted from runes, masteries, items, auras/buffs, and champion abilities. It does not include the target's base armor and the armor they gain per level.

Bonus armor penetration is calculated before percentage armor penetration. Since I recommend on Yasuo, let's use it as an example. When an enemy champion has 50 base armor and 150 bonus armor, 75 armor is penetrated from Yasuo's ultimate. The remaining 125 armor is then subjected to 's effects, leaving the champion with only 81.25 effective armor when attacked by Yasuo. Remember, it's Yasuo that gets the buff, so the armor penetration applies to everyone he hits.

Note that "Airborne," in League of Legends, is considered a form of crowd control caused by an opposing champion. Here are all 40 of them, in alphabetical order, that have abilities that cause airborne:

The more of these champions that are in your team's composition, the more opportunities Yasuo can cast his ultimate. Some are better than others, particularly the ones that can send multiple enemies airborne at once, such as or .

Ability Sequence, and Why

My preferred ability order is RQEW, and I recommend this order to anyone else who is new to Yasuo.

is your primary source of damage and has to be maxed first when playing AD Yasuo.

requires a summoner with a strong understanding of most champions, along with quick reflexes, to maximize the ability's full potential. Knowing when to employ the wall, whether it's to shield 's or to avoid damage from enemy flanks, is critical to success. Practice makes perfect but, in the meantime, I suggest sticking with maxing after since it's more straightforward.

However, don't be afraid to take before level 4. It's perfectly fine to take it at level 3 or even level 2 if Yasuo is against a champion with poke, like , or a mostly projectile-based toolkit, such as . See the active part of section W for the list of things it can block.

Runes

The Proposed Rune Page, and Why

5x Greater Mark of Critical Chance = 4.6% Crit Chance
The first half of 's passive, , gives double critical chance from all sources. Contrary to what the statistics currently say, the marks and seal will give Yasuo 10.2% critical chance.

4x Greater Mark of Attack Damage = 3.95 AD
Of all the remaining marks available, flat AD marks will work well with crit and helps with last-hitting and trading in the early game.

8x Greater Seal of Armor = 11 Armor
Flat armor seals continue to be the most effective ones to get for just about every champion.

1x Greater Seal of Critical Chance = 0.46% Crit Chance.
This anomaly is solely to get as close to 5% critical chance before going over, before applying Yasuo's passive.

9x Greater Glyph of Magic Resist = 12MR
Other primary glyphs such as ability power, cooldown reduction, energy, or mana either offer very little or absolutely nothing for Yasuo compared to Magic Resist.

3x Greater Quintessence of Attack Damage = 6.75 AD
Same reason for the AD marks.

If you don't have all of the runes, many of them can be substituted. However, I consider critical chance to be core on this build and thus cannot be swapped out. Skip the next section to the part where alternate runes could be used. Otherwise, continue reading to see how much IP it will cost to construct this page.

IP Cost Breakdown

The total cost to make the rune page above is 9,840IP. Here, I divided them and sorted the list by which ones you should most likely already have, so that you can make adjustments as to how much IP you need to actually spend.

8x Greater Seal of Armor = 1,640IP
9x Greater Glyph of Magic Resist = 1,845IP
4x Greater Mark of Attack Damage = 820IP
3x Greater Quintessence of Attack Damage = 3,075IP
5x Greater Mark of Critical Chance = 2,050IP
1x Greater Seal of Critical Chance = 410IP

Most people should have the first four types of runes, but will not have the critical chance marks and seal. For those that fit into this category, the adjusted cost is 2,460IP.

The Gold Value of Critical Chance Runes on Yasuo

The major difference in my guide compared to most others is that I opted to use critical chance runes over flat AD. One of the reasons why I think it's better is the gold value Yasuo get from having additional critical chance instead.

First, consider the gold cost of 1AD to be 36g (), 1% crit to be 50g (), and 1 armor to be 20g (). Next, we can calculate the following:

at 0.95AD = 34.2g
at +0.93% = 46.5g
With Yasuo's Passive, at 1.86%+ = 93g
Gold Difference per mark: +58.8g

at 1.41 armor = 28.2g
at +0.42% = 21g
With Yasuo's Passive, at +0.84% = 42g
Gold difference per seal = +13.8g

Adding everything up, (58.8g) * (5x marks) + (13.8g) * (1 seal) = +307.8g.

Since there is a hard cap of 100% critical chance, and my guide suggests to build and , I do not advise investing any more critical chance runes.

Upon completion of the two items, Yasuo is technically at 100.2% critical chance. The 0.2% loss is equivalent to 10g.

Other Runes To Consider

Greater Glyph of Scaling Magic Resist
This is a perfectly good alternative if you're not expecting to lane against an AP champion, which would then allow you to gain more overall magic resist for the team fights towards the latter stages of the game. Either is fine.

Greater Quintessence of Life Steal
Life steal is great for increased sustainability, but understand that it won't be as effective since we're only applying 4 AD marks instead of the usual 9. That being said, running these quintessences has great synergy with a start.

Greater Quintessence of Movement Speed
Having movement speed is nice on any champion, and using it on Yasuo will allow him to gain Flow more quickly, which means his shield will be available more frequently. However, increased movement speed is not as important because of , which helps him gain Flow pretty quickly already. Basically, Yasuo would lose his early-game damage for slightly more defense and utility. This is okay if this is the only quintessence available, but flat AD or even life steal is more valuable in this case.

Greater Mark of Armor Penetration and Greater Quintessence of Armor Penetration
If flat AD is to improve a champion's early game, then armor penetration is to improve their late game. That said, remember that Yasuo gains 50% bonus armor penetration after casting . Thus, I feel that it's a better choice to reinforce his low initial attack damage instead.

Masteries

Offense

Tier 1:

Double-Edged Sword - Critical strikes are a form of burst damage, which deal large amounts of damage in a short window of time. This mastery will amplify that further.
Fury - Increasing Yasuo's attack speed, aside from more basic attacks, will reduce Steel Tempest's cooldown.
Sorcery - This mastery is a playstyle alternative to Fury. This will reduce the cooldowns on Yasuo's abilities except Steel Tempest, which means he will become more defensive and utility-oriented. Still, I recommend Fury to promote a more aggressive playstyle.
Butcher - Yasuo doesn't have much difficulty clearing minions. Him being manaless, along with the fact that Steel Tempest can attack multiple enemies, makes Yasuo very forgiving in farming. This also scales extremely poorly into the late game.

Tier 2:

Brute Force - Equivalent to the gold value of a Long Sword at level 18, this is the only reasonable mastery for Yasuo to take at tier 2.
Expose Weakness - This can be an alternative mastery for Double-Edged Sword . Doing so will make you slightly more effective in team fights but make you slightly weaker in burst damage. Since more masteries will be invested in increasing damage coming from Yasuo only, I recommend taking Double-Edged Sword instead.
Mental Force - Ability Power only improves Sweeping Blade, which is not our primary source of damage.
Feast - Restoring 1 mana is worthless on a manaless champion, and 2 health is pretty terrible too. Getting the same value as one Health Potion takes 75 minion kills. No thanks!

Tier 3:

Spell Weaving - While not one of the best spell weavers, Yasuo's on-hit effects from Steel Tempest makes it relatively easy for him to gain stacks. However, note that the whirlwind itself will not proc Spell Weaving.
Martial Mastery - More AD!
Executioner - This is a great mastery for assassins like Yasuo, which will allow him to deal more damage in a short opportunity.
Arcane Mastery - We're not building AP Yasuo!

Tier 4:

Warlord - More DPS!
Blade Weaving - Again, Yasuo is not the best weaver. However, Blade Weaving allows for more damage during team fights where he can use Sweeping Blade on champions more frequently. That ability, along with Last Breath, are the only two spells that will gain Blade Weaving stacks. Because this mastery requires a good understanding of combos, consider Dangerous Game or 3/3 Devastating Strikes as alternatives if you're not yet comfortable with Yasuo's toolkit.
Dangerous Game - This is a bit more dueling-oriented compared to Blade Weaving and encourages a much more aggressive, all-in, playstyle. High risk, high reward. If this seems too situational, or if you're not really comfortable playing Yasuo in this manner, consider 3/3 Devastating Strikes .
Archmage - Nope!

Tier 5:

2/3 Devastating Strikes - Penetration offers late game damage when enemies start gaining armor and magic resist from levels and items. It's much better when the enemy team composition has 2 or so potentially tanky champions. Opt for 3/3 if that's the case, or if Blade Weaving and Dangerous Game seems too tricky to utilize. Remember, you also utilize magic penetration from Statikk Shiv!
Frenzy - Increased attack speed will reduce the cooldown of Steel Tempest and this will work more frequently, until always, when going for a 100% crit build.
Arcane Blade - We're not building AP, so 5% of 0 AP equals 0 extra damage.

Defense

In this tree, I'm consolidating the first three tiers and only making small comments on what not to get.

Tiers 1-3:

Block - Helps with early-game trading in lane. When using a Doran's Shield, blocking 10 damage per auto-attack is not bad!
Enchanted Armor - Great with surviving late-game team fights. Even if you don't build any defensive items (not recommended), it is still much better than Recovery in just about every case. 0.4 health per second? No thanks!
Unyielding - This also reduces champion damage by 2, but from all sources. Considering Block, Unyielding, and Doran's Shield, Yasuo can effectively block 12 damage per auto attack.
Veteran Scars - 36 health is not much, but it's required to access Juggernaut.
Juggernaut - Good late-game scaling. Additionally, the defensive items I've recommended such as Randuin's Omen will get more value from this mastery.
Tough Skin and Bladed Armor - This is for when you're jungling, which unfortunately this guide does not focus on.

Utility

Too many masteries in tiers 1-3 of of the Utility tree rely on the usage of mana. Since Yasuo doesn't use that, it's much better to invest most, if not all, of your points in the Defense Tree instead. The only possibly viable mastery would be , but note that movement is not really an issue with Yasuo when considering his .

Items

Note that the item order in the beginning of this guide is not set in stone. Build Yasuo however you like. I'm just here to make recommendations as to why certain items are better on Yasuo and why some aren't, therefore allowing you to make informed purchases. With that said, this will be sorted in the same manner as the cheat sheet.

Starting Items

Doran's Blade - The aggressive start is best against squishy champions that Yasuo can easily close in and deal damage. If you are running life steal quintessences, this is a good route to go with.
Doran's Shield - When laning against a ranged champion, especially with high health and/or armor, it may be better to run the shield instead. Doing so keeps you alive for an otherwise grueling first few levels. Masteries, the barrier from Flow, and Doran's Shield should keep Yasuo pretty healthy.
Cloth Armor - In very niche scenarios, Cloth Armor may fare better. I would recommend getting this when both the laning opponent and jungler are AD-based. This will also build towards Ninja Tabi.
Brawler's Gloves - A head start towards Avarice Blade or even Zeal. When also considering runes and Yasuo's passive, a 1/4 chance to crit at level 1 is surprisingly not bad. Just don't try this on Friday the 13th.
Health Potion - Whatever you buy, always spend the remaining gold on this.

Trinket

Stealth Ward - This trinket has the best synergy with Yasuo's Sweeping Blade, which can allow him to make some neat escapes throughout the jungle. It's the go-to choice in most cases, but consider swapping it out for Sweeping Lens to deny enemy vision towards the later portions of the game.

First Back Options

B. F. Sword - In the best case scenario, you've accumulated 1550+ gold and feel that your opponent is a pushover. If so, going for 45 extra damage will continue to punish your opponent.
Pickaxe - If you just need a little extra push to win against your opponent but you're far away from the BF Sword, this can provide a reasonable amount of damage. It helps build either towards the Infinity Edge or Last Whisper as well.
Avarice Blade - If there's a stalemate in your lane, go for this. If you can't beat your opponent, and vice versa, then getting more gold will put you in the lead.
Vampiric Scepter - If you're simply having a hard time staying in lane, this will help with providing additional sustain. This also builds into either Blade of the Ruined King or Bloodthirster, which are great aggressive options for Yasuo.
Boots - Unless you're planning to roam around really early, try to purchase any of the above four items first before getting boots. Mobility is not much of an issue thanks to his Sweeping Blade, but be sure to get it sometime around the purchase of Statikk Shiv. Shiv puts Yasuo at 371 movement speed, and boots at 375.

Rush

Statikk Shiv - Quite possibly the core of all Yasuo builds, the amount of synergy that it provides to him is simply amazing. Lower cooldowns on Steel Tempest, faster Flow gain, 20%(+20%) critical chance, and additional magic damage (that can also critically strike) makes this a high priority item to get.

One thing to note is that using Sweeping Blade will allow Statikk Shiv to gain 25 stacks each time, making the passive exceptionally fast to refresh.

Getting this item, with runes, will put Yasuo at 50% critical chance.

Boot Options

Berserker's Greaves - First, we must consider that Steel Tempest only requires an additional 55% attack speed at level 18 to reach maximum cooldown reduction. Fury , 3 stacks of Frenzy , and Statikk Shiv will put Yasuo at 60% attack speed. Since Yasuo gains 3.5% extra attack speed per level, having the Greaves will let Yasuo reach max cooldown reduction as early as level 13. However, since Yasuo can use Steel Tempest in between two auto attacks, it may not be more beneficial to have additional attack speed at this point.

Basically, if you're playing well in the early game, getting the Berserker's Greaves will promote snowballing even further. However, Yasuo can still get defensive boots without sacrificing the effectiveness of Steel Tempest.
Mercury's Treads - Crowd control is the bane of most melee champions, so having Tenacity is great in reducing the duration of most of crowd control effects.
Ninja Tabi - A good pick when your laning opponent and jungler deal attack damage.
Enchantment: Homeguard - If you're a fast shopper, this upgrade is always viable. You should definitely consider it when towers are being lost at an alarming rate, but it can also be used offensively to quickly get back into action.
Enchantment: Furor - This helps to stay close to your opponents when they're fleeing. Furor procs off the slash from Steel Tempest as well, so this is a good additional gap closer when Sweeping Blade is on cooldown.

For 100% Crit

Infinity Edge - If you're not falling behind by a large margin, going for IE at this point is a pretty good choice. This will stabilize Yasuo's critical chance to a whopping 100%. Basic attacks now deal 225% of base AD, Steel Tempest now deals an additional 88% of base AD per strike (up from 50% on crit), and Statikk Shiv deals 250 magic damage (it is not affected by Yasuo's crit reduction). These two items allow Yasuo to deal damage comparable to a marksman's basic attack damage in the late game, but at roughly 25 minutes in.

Aggressive Options

Last Whisper - Armor penetration helps to counter champions who stack armor.
Blade of the Ruined King (BotRK) - The passive helps to counter champions who stack health, while the active lets Yasuo both catch and escape from enemy champions.

It is not uncommon to see both Last Whisper and BotRK as a means to shut down tanks.
Bloodthirster - With the necessary crit items discussed thus far, Bloodthirster at full stacks adds an additional 225 physical damage on top. Ultimately, this additional burst is best preferred when the enemy tanks, if any, aren't relevant.

Defensive Options

Randuin's Omen - This is the only worthwhile armor item for Yasuo to get. The stats are appropriate, and the active also acts as a mini-AOE Exhaust and helps Yasuo to keep slashing enemy opponents if they happen to be slightly faster than him.
Maw of Malmortius - Aside from the stock magic resist, the passive allows Yasuo to mitigate damage from mages, especially from those with all-in combos. However, if you plan on having life steal in your build, or prefer cooldown reduction, opt for the following item instead.
Spirit Visage - The passive has good synergy with life steal items such as BotRK. The increased health and health regeneration is a nice plus as well.
Quicksilver Sash - If crowd control is a key influence in the enemy team's initiations, getting this item will allow Yasuo to break away and resume business. Get the Mercurial Scimitar after everything else in your build is complete.
Guardian Angel - Having this item can cause the enemy team to reconsider their means of engagement, especially if Yasuo is their main focus during a team fight.

Other Items to Consider

Ravenous Hydra - Since Yasuo's Steel Tempest can already attack multiple enemies really fast, the item's passive is practically redundant. Yasuo does not have difficulty with wave clear and the active is not as useful to Yasuo compared to the Blade of the Ruined King. I would opt for that or Bloodthirster over this pretty much every time.
Zephyr - Remember that Yasuo only needs 55% increased attack speed at level 18 to reach maximum cooldown reduction on Steel Tempest. Statikk Shiv is already considered core, so having even more attack speed with little damage to back it up makes the Zephyr a pretty poor choice. If Tenacity is of concern, then simply buy Mercury's Treads. If you still want attack speed, the Blade of the Ruined King is a much better option.
Banshee's Veil - This is what you can get in lieu of Spirit Visage. It's really good against burst mages who'd use a combination of abilities to deal massive damage in a short window. Examples include LeBlanc, Akali, Ahri, Kassadin, and Veigar. Having the shield will at least block one of their abilities and potentially mitigate a good portion of damage. If the enemy team doesn't have anyone that fits this description, then having a Spirit Visage is preferred.
Black Cleaver - If the team's AD carry (or marksman) is doing a pretty good job while Yasuo has a lot of assists, it may be better to opt for this to help amplify their damage instead. Only one person on the team needs to build it, though. If someone else, like your tank, decides to, you should build Last Whisper instead.
Youmuu's Ghostblade - The Ghostblade promotes the assassin-like qualities of Yasuo by offering a mini- Ghost as its active. Flat armor penetration also works great in the early to mid game against squishy champions. Along with that reason, I would recommend it if your team is lacking in the AD department and also notice many key players on the enemy team not building much armor.
Trinity Force - At level 18, Trinity Force brings an extra 216 (108 base AD x2) physical damage to Steel Tempest. That's pretty good, but note that the passive only affects the first target hit, not all of them. The passive also does not crit. Therefore, in a team fight, it's very important that Steel Tempest hits its intended target first. Unfortunately, tanks are usually at the front lines, protecting their carries, so it may be difficult to sneak behind them without using Last Breath. On the other hand, Statikk Shiv's passive has the potential to bleed behind the tanks and deal around 250 magic damage to up to four champions each. That's about 585 extra raw damage in comparison!

Overall, It's a good alternative, but I feel that Statikk Shiv does more damage in team fights, while the Trinity Force's two passives makes it better for punishing enemies that are out of position.
Phantom Dancer - Some people originally got this over Statikk Shiv to obtain 100% crit. With the runes in place, this item pales in comparison. Pairing Phantom Dancer and Infinity Edge, without runes, totaled to 110% critical chance. The 10% excess is basically 500g wasted on top of the 300g it took to get Phantom Dancer over Statikk Shiv. The passive to move through units is also pretty negligible when considering Yasuo's Sweeping Blade, which allows him to pass through them much faster anyway.
Thornmail - Yasuo doesn't come with large stocks of health to utilize its passive for any extended amount of time. It's better reserved for actual tanks.
Sunfire Aegis - Yasuo is a "get in, deal damage, get out" kind of champion. As such, he generally won't be in close proximity of enemy champions for very long. The passive is better for tanky champions who can harass the enemy team close by for longer durations.

Summoner Spells

Core Spell

Flash - Despite how much I praise the movement that Yasuo gets from Sweeping Blade, ultimately it cannot be relied on for every escape. Flash, on the other hand, can be, with the addition that it can be used to secure kills. This spell is viable on every champion, but I feel that it's especially important that you take it for Yasuo among everything else.

Viable Spells

Ignite - There's going to be a few situations that Yasuo will be a few steps shy of a killing blow. It's frustrating, so that's why this is one of the most commonly taken spells. It allows Yasuo to secure kills and allows for more successful all-in dives.
Teleport - Great option for aspiring mid-lane gankers everywhere! This is for play makers with good map awareness.
Cleanse - This has to be picked on a per match-up basis. It's imperative to know if the opponent often relies on a form of crowd control before they deal damage, like Ahri.
Barrier - For the more conservative Yasuo player, this is good when going laning with another melee opponent that you feel like you're going to do poor against. If they tower dive you, popping the barrier will force them to either extend their stay (and possibly die as a result) or back off.
Exhaust - Ideally, one person on the team should have this. You can use it, but it will be less effective in the laning phase if the opponent has escapes or doesn't rely on auto attacks.
Ghost - While viable, I only recommend getting this only if you don't have Flash. They serve the same purpose, but sustained movement speed is not something that Yasuo needs.
Smite - It's a fine spell but only if you're jungling.

Spells to Avoid

Heal - Barrier is usually a better option since the effects of Heal can be halved by Ignite, which many solo laners take. Barrier does not suffer from that effect, and it also has a shorter cooldown of 90 seconds in comparison.
Revive - This has only really been decent on Karthus, where he's able to cast spells even after taking fatal damage. Even so, coming into the match expecting to die often is a poor outlook, so I would seek something else.
Clarity - Well, sometimes your support might need mana. However, Yasuo won't.
Clairvoyance - Use a Stealth Ward instead.

Closing Thoughts

This concludes my core descriptions about the item build for this champion. If this gets enough traction, I'll spend some additional time showing the numerous combos Yasuo can employ during the laning phase, and which areas he can use to dash through the jungle.

Thanks for reading!