I created this Vi build guide after I played a match where our team had enough Tanks and Bruisers.
Basically I wanted to play Vi in a way that would be surprising to the enemy.
Because Vi already deals a lot of Burst Damage I decided to make an On-Hit sort of Vi build and here it is.

When would you build Crit Vi?

Play with this build whenever your team has a frontline and the enemy does not. Build these items into a squishy enemy team.

Pros and Cons

+ You deal a lot of damage in a very short time while still being a good duelist.
+ Vi's strong early game allows her to snowball into the late game.
+ Crit Vi surprises the enemy team with the damage it deals.

- If you get cc'd you are very easy to kill.
- Weak into a Tanky team.

Vi has 3 active abilites and 1 passive ability on top of the standard passive.

Vi's Passive gives her a shield after hitting one of her abilities (Q, E, R). The shield has a cooldown that gets reduced by 3 seconds whenever her W triggers.

Vi's Q can be casted twice. While casting it for the first time you charge the ability up. The higher the charge, the further you dash. If you hit an enemy champion, it will stop your dash. If you don't hit an enemy champion, you can dash through terrain and minions or monsters. When you hit minions or monsters, you will knock them up and bring them behind where your dash ends.

Vi's W is a passive ability. Whenever you hit an enemy (Q, E or Auto-Attack) the enemy gets a stack. When that enemy gets 3 stacks, the passive will trigger dealing more damage, and removing a percentage of the enemy's armor as well as granting Vi Attack Speed for a few seconds.

Vi's E is an active ability that works as an Auto-Attack. Basically Vi Auto-Attacks dealing AoE damage in a cone shape (like Titanic Hydra). This ability works as an Auto-Attack reset. Vi's E has 2 charges at the most. The ability has a shorter cooldown than it takes to regain a charge; basically you can cast your E every few seconds eventhough you only get a charge every 10+ seconds.

Vi's R is an active ability that knocks an enemy up as well as knocking enemies in your path aside. You point at one enemy and you knock that up then slamming them into the ground dealing lots of damage.

Vi has a few combos that are very easy to do. As the only skillshot you have is your Q, it is hard to miss a combo.

In this Combo guide, AA stands for Auto-Attack.

The easiest combo only uses your E while also triggering Vi's W dealing a lot of Burst Damage. If you have the Electrocute Keystone, this combo will also trigger that.
AA > E > AA After the last AA, your W and Electrocute will trigger.

Engaging Combo, mostly used for ganking or closing the gap between you and your enemy.
Q > AA > E As your Q applies a stack of your W, you will trigger your W and Electrocute.

All-in Combo for the most amount of CC on a single enemy.
Q > AA > E > AA > E > R

Whenever the enemy is running away, you can catch up with the using Q or R.

Because Vi has a really strong early game, your jungle clear will be fairly easy. This build is not the best at powerspiking early in the game, but Vi's strong early game makes up for that.

Vi can do a full clear from either side of the map. Depending on where you want to gank first you should decide if you start in your bot jungle or top jungle.
If you want to gank top first, you start bot and if you want to gank bot first, you start top.

As Vi's clear is pretty fast and healthy, I do a full clear:
Starting from Blue: Blue Buff, Gromp, Wolves, Raptors, Red Buff, Krugs

Starting from Red: Red Buff, Krugs, Raptors, Wolves, Blue Buff, Gromp

After this clear I always try to get at least 1 Rift Scuttler and then I start looking where I can gank.

From the first gank on, every game is different. Try to balance ganking and farming. Pro tip: never waste time. No matter where you are going, take camps that are on the way to your destination. Taking camps and ganking means you are getting XP which means you are getting stronger.

Whenever the enemy jungler dies, invade their jungle and place vision wards (Control Wards or Stealth Wards). Don't be afraid to take their camps as you can use your Q to get away. Taking the enemy jungler's camps means you are denying them XP which puts you and your team ahead.

For Items you have lots of options. In this guide I will only be showing you how to play with a Crit Build on Vi. Because Runes are the same for this build as for the Bruiser build, you can always choose to go for a Bruiser build when you are in-game.

You want to be rushing the Noonquiver as well as the Berserker Greaves. They give you a good powerspike in the early game and are not too expensive.

The main items you want to be getting are Galeforce and Essence Reaver.

Why Galeforce? Galeforce has very good stats and a dash that you can use when your Q is on cooldown. Galeforce gives you Attack Damage (60), Attack Speed (20%) and Critical Strike Chance (20%). It also grants every Legendary item 3% Move Speed, which is the main reason why I chose this item. Vi is not the fastest champion, so this item will help assassinating enemies.

Berserker's Greaves are the boots you want to be getting. They give a lot of Attack Speed and will help you get your combos off before the enemy gets away.

Essence Reaver has the passive from the Sheen built in. It allows Vi to deal a lot of damage in a very short time. As of now, it deals 100% Base Attack Damage + 40% Bonus Attack Damage. Because of its low cooldown (1.5 seconds) you can use this passive twice on the same enemy (if they aren't dead already).

I chose Stormrazor as a fourth item because Vi already deals a lot of damage. Stormrazor will deal some magic damage, but it also slows enemies by 75% for 0.5 seconds, which doesn't sound like a lot but it will make your enemies panic. On top of that, it gives you Critical Strike Chance (20%), Attack Damage (40) and Attack Speed (15%) only for 2700 gold.

As a fifth item I chose to go for Infinity Edge. Not only does it give you more Attack Damage (70), it also gives you more Critical Strike Chance (20%). You will now have 80% Critical Strike Chance so there will be a huge chance for you to deal a lot of damage. The passive from Infinity Edge gives Vi another 35% Critical Strike Damage, so your Auto-Attacks and your E hit even harder.

As a final item, I wanted to be able to fight tanks as well. Because this build focuses champions that don't build a lot of armor, you will have a hard time fighting tanks. For this reason I chose to go for Lord Dominik's Regards, which gives you 35% Armor Penetration. It also increases your Critical Strike Chance to 100% so every Auto-Attack and every E deals a lot of damage. More interesting is the passive of the item. Vi will deal 15% Bonus Physical Damage to champions that have more health than herself, so basically against Tanks.

The stats that you get from these items are:
- Attack Damage
- Attack Speed
- Critical Strike Chance & Critical Strike Damage
- Armor Penetration
- Movement Speed

At Level 18 with Full Build you will have the following stats:
Attack Damage: 373
Attack Speed: 1.40 (1.397/second)
Critical Strike Chance: 100%
Armor Penetration: 35%
Movement Speed: 428

To minions you will deal 1,000 damage per Auto-Attack.
To a Dragon with 51 Armor your Auto-Attack deals 708 Damage and your E deals 1,387 Damage.

To a Champion with 100 Armor you deal 475 Damage with a normal Auto-Attack. Your E deals 743 Damage and the W trigger deals 579 Damage with a normal Auto-Attack and 847 with your E.

Your late game is very straight forward.
Try to splitpush whenever you can. If you are ahead of the enemy jungler, you can most likely 1v1 anyone of the enemy team.

If you can't splitpush, just stick with your team and make as many picks as you can. Thin the enemy team out and then push for an objective (Turret, Inhibitor, Dragon, Baron).