Pros:
+ Best late game ADC
+ Long range ultimate
+ Amazing Late game burst
+ Camo
Most Important thing: Twitch is fun and can carry hard :)

+ Twitch is just super fun and amazing late-game. With his critical strike chance and Spray and Pray's bonus range and ad, he will be able to delete squishy and even tanks in the late game !!!

Cons:
-very, very weak early game
- Squishy
- Weak to hard CC
- Will start to scale after 2 items.

- Twitch is so bad early game. He can be bullied very easily by strong champions like Draven or supports with High CC. It is also very hard to fight in lane without his ultimate (Spray And Pray).

Passive

Deadly Venom: Twitch's basic attacks infect the target, dealing 1/2/3/4/5 True Damage every second for 6 seconds, stacking up to 6 times. The amount is increased every 4 levels.

Q

Active: Twitch becomes camouflaged for a duration after 1.5 seconds. Entering stealth cancels Twitch's current basic attack. Basic attacks and abilities break the stealth on-cast.


Twitch becomes Camouflaged for 10/11/12/13/14 seconds. While Camouflaged, Twitch gains 10% bonus Movement Speed. He gains additional movement speed when moving towards an enemy.


Ambush's cool-down is reset when an enemy affected by Deadly Venom dies.
If Twitch takes any damage while casting Ambush, the activation is delayed to 4.5 seconds.

Ambush (Q) gives you a really nice attack speed boost. You can use your Q to position in team fights. The Attack speed is godlike when combined with your ultimate

W

Venom Cask: Twitch hurls a cask of venom that explodes in an area, adding 1 stack of Deadly Venom, leaving a cloud of toxic gas that slows enemies by 25/30/35/40/45% and adds a stack of deadly venom every second to enemies inside of it.
The cloud lasts 3 seconds.

Venom Cask is Twitch's only real way to stick to his targets, and his most important trading tool in lane. It's slow can allow your support to get a good engage on the enemy if they're hit directly by it, which will likely result in a won trade. Be careful, though - the enemy can capitalize on your Venom Cask being on cool-down and hard engage on you.

+ Good trading tool in lane. Slows your enemy's so that they cant run away.

E

Contaminate Deals 20/30/40/50/60 Physical Damage to enemies affected by Deadly Venom. It deals an additional 15/20/25/30/35 (+20% Ability Power) (+.35 per bonus Attack Damage) Physical Damage per stack of Deadly Venom on them.

Massive AOE DMG with your ult and Runaan's Hurricane

R BABY

Spray and Pray: For 5 seconds, Twitch gains 300 attack range, 20/30/40 bonus Attack Damage, and his attacks become piercing bolts that deal 20% less damage to subsequent targets, down to a minimum of 40%.

Nothing to say Just Spray and Pray.

It is the reason why he is so amazing late game. Amazing AOE damage in team fights.

IMPORTANT Spray and Pray can be activated in your Camouflage from Ambush(Q), and you won't lose the effect.

Position with your Q before you use your ult. (You will also get good Attack speed)

Leathel Tempo

+ Decaying Attack speed
+ Good combined With Runaan's Hurricane

PRESS THE ATTACK

+ Good burst.
+ Massive damage late game
+ Auto attack champion

TRIUMPH

+ Extra suvivability
+ Clutch heal in fights

Legend : Alacrity

+ Very good for any marksmen.
+ Attack speed

Coup de Grace

+ More DMG is always nice

Sorcery



Absolute Focus

+ More dmg while above 70 % health

Gathering Storm

+ Gives you good amounts of AD

Don't copy-paste the build every game. You need different items in different situations.

Blade of The Ruined King :

Should always be the first item.
+ Great stats
+ survivability
+ Great scaling
+ Yoinks movement speed

Runaan's Hurricane :

Should always be your second Item.

+ Can hit multiple targets with Spray And Pray (R)
+ Better Wave clear
+ Critical strike

Infinity Edge (IE) :

+ Amazing on any Crit champion
+ Gives enormous Power spike

Phantom Dancer :

+ Even more Crit.
+ You will have reached 75% Critical strike chance.
+ More survivability with passive (Lifeline)

Rapid Firecannon :

Take this or Phantom Dancer.
+ Rapid firecannon will give you more burst
+ extra range
+ dmg to towers

Lord Dominik's Regard / Mortal Reminder



+ Lord Dominik's Regard is great if the enemy team is building armor.
+ Mortal Reminder if they have a lot of healing

Guardian Angel (GA) :

+ More armor
+ Revive

Play safeand farm. Your W is a good slow and poke in lane.
FARM! FARM!

In the lane phase you will want to focus on farming. Twitch is a late game hyper carry beast. So focus on farming. You will need early items to fight in lane. You can poke with W and e. Wait until the last second to use Your E as it does more dmg with more stacks.

If you have a hard engage support like Blitz or Nautilus, it can be beneficial to go for kills, however it is often better and of less risk to farm safely until you hit your power spike (around the first item).

You will hit a power spike after getting Blade of the ruined king and Runaan's Hurricane.

When you want to go all in with your support. Position yourself first with Q and then use R.

It is risky to fight without R (would not recommend)unless you get a gank.

When you are going for an all-in you are gonna have to position yourself with your Q. Your Q also gives you a pretty nice attack speed buff combined with your ult. You are gonna have to position with your Q, because if you get jumped... Youre dead. Unless you have Flash or your support saves you.

You have to be CAREFUL in lane. you have no mobility or escape. The only real escape you have is flash. You should nearly always let your tank engaqe first.

Position with Q
Delete players with ult
Guardian Angel is a very good late game Item for team fights
Do not try to 1v5
Wait for your team to go in and Tank (Frontline)
Stay in the back and kite if necessary

- Win

As twitch, you get a special role. As both assassin and adc. You can wait to go in with your team. Or you can roam the map with your q and try to look for an easy kill before your team engages. Twitch is really good at killing 1 target (1v1). With his Blade of the ruined king, attack speed from Q, ultimate, and slow from w, Twitch can kill nearly any squishy target in a 1v1.

- Position with your Q
Focus the targets you safely can hit or the one closest.
Activate R to hit multiple targets.
You can wait for the enemy team to group and then come out of your Q stealth, and then just Spray and pray with R.

Again position with your q. Your q has a pretty long cooldown so you will have to use it wisely. Pop your ult.Focus on the targets you can hit on the frontline. You are also gonna hit the entire team or enemys behind the frontline with your ult, so you can do a lot of burst dmg really quick. Again, you have no escape, so remember to position correctly. A dead adc is a useless adc.

Your q resets after each kill or assist. After getting an assist or kill you can use your q to get another kill or position again.

W has a good slow which can be useful against enemies that are close together. Try to wait with using your E until you have max stacks.

Sometimes it is best to let your team engage before you go out of your q stealth. This way the enemy team may use their engage abilities on other teammates. This, of course, lets you sit back and ult from a safe distance, which should win you the team fight,(Most of the time O_o). If you do not have ult at the beginning of a team fight, look to get a kill and then immediately go into stealth(q). This lets you look for more kills by stealthily sneaking around. If you are ahead, you should be able to solo kill an enemy that is misplaced.

This is my first guide.. so be nice xD
It is not very pretty but I think it is short and sweet.
Constructive criticism or just general criticism will be appreciated ;)
Thanks for reading <3 much love