Lets just get down to the nitty gritty... (All constructive criticism welcome) Before reading I this guide I would also like to say that I am a quantity>quality on the crossbow bolts style player.
I feel no need to post Twitch's stats/bio/skills. This guide will only be my preferred items/skill build/thoughts on playing Twitch.
Also I am no means a High Elo player.
I start with expunge, and alternate it and Ambush until 6 or until I have to take Debilitating Poison
Red = Armor Pen
Yellow = Crit Chance
Blue = CDR/Level
Quints = Flat HP
21 Offense/9 Utility
Reasons behind these choices:
1)Skill preference: I choose to skip debilitating poison in favor of having exhaust and the fact that you should be keeping the Lizard Buff constantly. My skill build varies if there are other champions that I feel need the Lizard Buff more than I do, I.E. I pick up debilitating poison at about level 7.
Armor Pen for Red is just a good all around choice, some people say that Crit chance is favorable and I have tried both and prefer armor pen. With my item build crit is not 100% preference.
Crit Chance for Yellow is what I use because there are no other runes for yellow that seem worth it. (open for suggestions with good reasoning/explanation behind them)
CDR/Level for Blue, I use these because at max level with the Golem buff these put you very close if not at the cap. More Spray and Pray = more rape, and faster Ambush so you can get the hell outta dodge
Flat HP for Quints to help Twitch not be so **** squishy early game
Cleanse: This is your god send against stuns/silences/slows
Exhaust: Good early game ganking ability, great for late game survivability. I say survivability because when you unstealth behind the back lines in a 5v5 fight and there carry Flashes to you to crush your face in, this stops him for long enough that your team can crush him and effectively make it 5v4. This combo'd with Cleanse can keep you alive in those 5v5's and make sure that your Spray and Pray is used at full efficiency.
Pretty tried and true 21/0/9 here. Improved exhaust is your friend, great for shutting down there carry when he catches you off guard.
My play style:
I usually prefer not to solo lane, this allows you to go around and gank and not leave your lane completely undefended, plus it is very easy to go unnoticed when you go MIA from the bottom lane. Top lane hardly expects it when you show up and mow them down at level 6 with a well placed Spray and Pray when they are pushing your turret, or trying to hide behind theres.
When my lane is pushed all the way up to there tower and i'm expecting a gank me and my teammate will fall back. This gives you plenty of time to go grab Lizard buff, and kill the small wolf/golem camp.
Golem buff is your friend late game, I don't consider the CDR/Mana from it necessity early game. Being conservative with your mana will make it so you don't need it.
One thing I don't see alot of Twitch players do is use stealth to get that free exp when laning against harassers. Just stealth up and walk close enough to the mobs to get the free exp. I also do this when my lane partner recalls and I don't want to take the chance of getting ganked.
Twitch is very squishy early game and that is why I take the HP Quints, these help offset this, but in no way make you tanky enough to go 2v1 before you have a good chunk of your items.
Also if you know that the enemy team is dropping Wards like crazy, I usually delay my item build to get an Oracles Elixir. This makes so many people rage when they drop a "well placed" Ward and you just gun it down and dip out before they can do ****.
I almost always get an Oracles when fighting Teemo. Accidently setting off one of his shrooms when trying to set up a good Spray and Pray position almost always means one dead rat.
1a) Port back when you have enough for Malady, or if you are doing well in kills go back and get number 2 also
2)Berserker Greaves. I hear some people say Merc Treads are great on Twitch, but you are squishy enough that these won't help you, this is also why I sport Cleanse
2a)Boots of Mobility. I sometimes pick these up and sell my Berserker greaves late game if it looks like we're going to have to back door to win, shaving precious seconds off of your travel time can make the difference between a win and a lose. If you use these though you won't be at max attack speed without spray and pray though
3)Recurve bow. Not getting enough kills? Buy this then build Last Whisper. Raping their faces off? Wait until you have enough for just Last Whisper.
**With these 3 items and your Ambush your are at about 2.479 attack speed**
4)Infinity Edge. Always try your hardest to get B.F. Sword first, follow by the Pick Axe, then don't come back until you can complete the Edge
5)This is where the build can vary. I have been tinkering around with Tiamat against melee heavy teams (a.k.a. stacked up in team fights) With Spray and Pray and Tiamat it seems to be more damage output than anything else against melee heavy teams.
5a)As I said before this is where it varies, most games are over by now anyway though, but Enemies stacking armor? Black Cleaver because it helps your whole team, Madreds if they are stacking tons of HP.
6)If for some strange reason a game manages to last this long, you are on your own I would probably go with some more damage, or some life steal, its really up to you at this point. Most likely Tiamat if you didn't get it earlier.
I have played with this build in Solo Queue, and every style of premade, it works very well for me and suits my play style with Twitch. As I said at the very beginning of this guide I am very open to discussion or any constructive criticism.
Hope you guys/gals enjoy it and have fun mowing *****es down with this.