This build is very selfish but also helps the team a lot.
Build this after you have practiced at least a bit of Twitch.
You can change the build to your likings.
You need a properly skilled team to do this.
This build can be built in any ELO.
You can build this even in low level.

Hello i am GPOhdx or also TRD Naibory,
I really like Twitche's playstyle, his abilities, the fact that he can be a hyper carry and just Twitch overall. This is a Twitch guide for all of you players who like Twitch just like me but can't really find the right build on Twitch. This build will carry if you play correctly.

If you want to see how sucessfull this build is then view my Match History with Twitch here
I know it is not much but in those games we crushed the enemy Team.

Early game:
-Farm early.
-Stay out of combat.
-Ward defensively only.
-Fight only if Teamfight breaks out nearby
Mid game/Late game:
-Stay behind in the Teamfight an deal damage from afar.
-Do not go too deep.
-Try to push towers.
-Do not underestimate your opponents and get cocky.
-Always stay with atleast 1 teammate.

As a Twitch your Early game is very difficult because the other ADCs will bully you, but once you get Blade of the Ruined King and Runaan's Hurricane you will be able to farm and since you have Cull you will also get that extra gold. Once the Teamfights start you can use your Ambush ability to go in and shred them with your ult Rat-ta-tat-tat and because you have Runaan's hurricane you wil spread your Deadly Venom to all your enemies. When the most of the enemies have a lot of Deadly Venom stacks you can use your Contaminate and do massive damage or even kill them.

Red buff synergises well with your passive so that you have lots of true damage on your enemies, and since you have so much true damage you dont really need a last whisper.
With this build you are very squishy so do not overextend.

-Deadly Venom-Passive
Every Aouto Attack you poison the enemy with a stack of your Deadly Venom that deals true damage to the enemy every second for 6 seconds.
-Ambush-Q
After not taking damage for 1.5 seconds you go invisible. When you get visible again you get an Attack Speed bonus.
-Venom Cask-W
You throw a Cask full of Venom, giving all enemies that are hit two stacks of Deadly Venom that also slows the enemies for 3 seconds.
-Contaminate-E
You deal damage to all the enemies with Deadly Venom stacks. The more Deadly Venom stacks the more damage you deal to the enemies.
Rat-ta-tat-tat-Rat-ta-tat-tat-R
You gain 300 Range and deal bonus Attack damage. Your Auto Attacks also pierce through the enemy.

=Pros:
+ Very high Damage
+ Awesome sustain
+ High carry potencial
+ Superb Wave clear
+ Crushing teamfights
+After getting fed dominates lane

=Cons:
-Very squishy
-Weak early game
-Build is very expensive
-Mana hungry early
-Must get past early game

I am sorry that this is not finished yet but i will complete this soon.
I know this isnt the best build you will ever see since this is my first Guide so I hope this helped you at least a bit to learn how to play Twitch.