Twitch is a very OP late game champion,but he is risky to play because his not very usefull in early game by himself,you should always be able to solo out enemy ADC,APC and SUPP (talking about lvl 18 with this build i presented).How? 1st of all go into stealth before enemy can see you,next,come as close as you can,activate Youmuus Gosthblade,throw you W,stack with your basicks as much as possible and detonate with E.In larger team fights when you activate R you will see that your range is begger *** well so i recomend to do that immediatly after you get out of stealth and ofc,after activating Youmuus Gosthblade and throwing w with will possibly stack on and slow 2-3 even maybe 4 enemies if you catch the right moment,ulti applies stack and damage to 3 enemise so look out for your possisioning,dont be too close so they can catch you,be somewhere on the side when you can damage enemy ADC,APC and supp,after you kill these 3,it will be most likely 2 tanks who stayed to fight 4 or 5 of you,which means you got the team fight.With these tactique you can easily turn matches around and make some insane plays as well as good backdoors. THIS BUILD WILL MAKE YOU SQUISHY AS HELL SO WHATCH OUT FOR AMBUSH CAUSE NO ONE WILL BE ABLE TO SOLO YOU OUT..

Well as i said,you shouldnt go fully agressive at the start of the game cause at that time Twitch is weaker than most of his enemies.You could use your abilities to out farm your opponent but it will leave you semi-low on mana so dont think about engage,engage only after few(talking about bot lane early fights 2v2) items and when you are sure that you can burst down your enemies hp bar very quickly.Twitchs stealth you can use at early point like scouting enemie jungle or even killing him(if hes low and you happened to have ward,and you saw in which direction hes going)I would recomend that if your support doesnt have ward or they expired you should always farm near bush,so if you get ganked by jungler you could use stealth while in bush and safely get out of that situacion(you will need some time to enter the stealth,that time become longer if enemy is hitting you,thats why you need to get into the brush,gain stealth quicker while they cant attack you if they dont have ward in it,so they will have to come into the bush,but doesnt matter cause you will be stealthed and running aways as they try to bind you on blint etc.Morgana,Leona,Thresh,Blitzcrank...) If you want to kill your opponent early,get back,press B so he can see you recall,then move little back so he cant see you anymore,get into stealth and ambush him,he will think he can cs for free at the time but theres no way he can outplay you when you suprise him like that, unless hes very good player with incredible mechanichs stand little behing him,like melee range he cant get away,he may use flash aswell imediatly but dont worry,if he did he wont have it for some time and you will be able to kill him before he got it.So at the beggining of the game just go for secured kills dont risk anything,otherwise you could easyly end up feeding,just try to outfarm enemy and poke him as much as you can.In large team fights stay at the back,dont let them catch you,it would be good if you used Q before the fight so you could get attack speed,use E to apply stack to enemies then R so you can back off a little(it will give you extra damage,range and it will hit 3 enemies at the time,so its very usefull in large team fights) try to maximise stacks to each of your opponents and then trigger E,dont use E immediatly,you must w8,for a right time,to stack your passive some more.With this build and game style you will be killing machine and also very easy target if theres 2 or 3 enemies ambushing you,after stealth no one will be able to solo you out,element of suprise is on your side and also your biggest advantage,burst that you will be able to use if you know to use it right.