Last item offensive
Threats to Twitch with this build
|Sona||Sona is THE champion to take Twitch against. If your support is able to catch Sona at level 1-2 you'll always get a kill because she's so weak early on. If you get that early kill on her, she's just free gold from there on out.|
You'll read it a ton of times in my explanations but Twitch is one of the best, if not the best, ADC to fight level 1-2. The reason for this is because of the burst your E gives you. Try to get a kill early on, without using too many resources such as flash/heal. Depending on who you're up against you'll either play passive and farm until you've got your core build, or wait until level 6 to start roaming the map.
Mid game for Twitch starts when you've gotten your core build. During this time the teamfights usually start, and during this time you'll also be looking for champions who are out of position. When you stealth up right next to them you can burst them down thanks to the extra attack speed from your Q. Do choose your matchups wisely, becuase someone like LeBlanc or Zed would be happy to fight you if you try it.
Not a lot has changed from the mid game. The biggest choice you'll have to make is wether or not you can safely backdoor a turret/inhib etc. Just play dependant on how the game's gone, position yourself in such a way that your ult hits the most people and stay in the backline as much as possible.
Pros / Cons
Pros of Twitch:
Good escape with Q.
Can snowball hard if the enemy doesn't ward properly.
High kill potential early on.
High amounts of damage when fighting in chokepoints.
Low attack range without ult.
Damage doesn't come instantly, has to attack several times first.
Can be caught out of position very easy.
Early you need to have your support get a pick on one of the two opponents down bot, if the match allows to do this.
During teamfights you need to try and have your team bait the fights in the jungle so that the attacks during your ults hit as many enemies as possible, this is also the reason you get a high amount of attack speed.
When you're roaming it's wise to let your team know what you're up to, so they can possibly set something up on the other side of the map. If you, for instance, kill the enemy ADC down bot, and they threaten to take baron, you could keep pushing for the enemy turrets down bot putting the enemy's in a really bad spot.