Hello everyone. Ajdt29 here. This is my first build ever on mobafire. But that's not very important. Lets talk about the character that I'm showing you guys, Twitch.
Twitch is a very good late game dps but his early game isn't that great. His poison helps half of his spells so that's gonna help you take down the person. With Twitch you want to try to stay in stealth so that it forces your opponent to retreat or else they will get killed. Also his stealth is a great tool to escape. But you need to make sure you have a distance from the enemy or else each time they hit you, they can see you. So keep your distance when your going stealth. Now for the rest of the build.
For those of you looking for a dominion build, I will add one soon.

21/10/2011: added chapter "situational items"

17/11/2011: seeing how bad my build is; i redid it.

Pros

Late game is very good at dealing a bunch of damage to the enemy
Can surprise enemy with a gank because of stealth
his ultimate is a great way to get enemies that are trying to sneak away
his slow can help your team a lot in chasing or running away.
poison allows you to kill opponent even if you die (if opponent is low enough ofc)
and it will take a lot of people to take him down

Cons

In early game you need to be careful because twitch can be taken down easily
If someone has oracles, try

NOT to sneak up on him or else he will see you
if someone put in vision wards it will be harder to sneak away and to gank with Twitch
if your not aware of what the enemy is doing (letting you push, ganking, etc) you will die
Twitch's only escape is his stealth
and he will be focused because people don't want a fed twitch

I have attack speed marks and glyphs so that you can get a lot of poison on to the enemy.
I decided to use greater seals of resilence so that you can survive easier.
The quintessences are armor pen because it will just help shred the enemy to bits.
So with these runes I can go and deal a lot of damage to the enemy while just surviving the fight.

I used a 21/0/9 setup because in this way it will give me more damage. I used the 21 points in offense to mainly get more attack damage and attack speed. I also took a point in upgrading the Exhaust and Ignite spells so that you can take down the enemy better and if they are getting away, they can't. I used the 9 points in the utility so i can have a bit more mana, a little bit more move speed, a little bit more gold per second, and even to reduce how long you're dead. With this setup, I am able to get the most out of this character.

I started out with boot's of speed and 3 Health Potion so that if i get into a level 1 team fight, and lose, i can escape easier. Also for when i escape, i have 3 health potions to help me get back on up to full health. I get Mobility Boots so that i can roam around the map more. Next i get a Banshee's Veilso that I am allowed to have more magic resist, health, and mana. The spell shield is really handy too. Then i get an Aegis of the Legion. I get the Aegis of the Legion so that my character can survive even better now. Now i get a Phantom Dancer for even more attack speed, more critical chance, and a bit more move speed. Next on the list is a Mardred's bloodrazor. I do this so that i can have even more attack speed and a little bit more damage. This item is very handy for those who have lot's of health. Finally, I finish my build (if the game lasts that long) with a Zeke's Harbinger. This allows for even more attack speed and to have 20% lifesteal. It has a bunch of other effects too. The reason i am focusing mainly on attack speed for my offensive items is because of expunge. If you can land 6 attacks before expunge then you will do fine.

Now here comes some situational items. If you find that the enemy carries are taking you down easily, even with the Aegis of the Legion, then i would suggest a Thornmail. This bad boy will kill them all too easily.

I start out by maxing expunge so that my character can deal a lot of damage. I keep debilating poison and ambush equal because you need the slow from debilating poison. But you also need the stealth from ambush to surprise them and to escape. I take my ult whenever i can at level 6, 11, and 16. With this way you'll be balanced out so that you can slow and do effective damage.

I choose Exhaust and Ignite so that i can kill my opponent and so that no one can really escape. The other choices that i would say are Flash and Teleport. Flash to get away from them and teleport so that if anyone tries to backdoor or your soloing you can easily make it back to that lane. Another good choice might be Ghost. Ghost + ambush is a very nice combo.

Early game
Your gonna want to start off by farming but safely because, as i said earlier, his early game is weak. As soon as you get the infinity edge you can start killing the enemy better. But before Infinity Edge, keep quiet but still get gold. If the opponent is trying to harass you, keep your distance or stay behind the minions.
mid game
By this time you should have your Infinity Edge so you can start dealing some damage. Start harassing the enemy if they get too close but try not to get into a fight with the enemy just yet. You can't take him down quickly enough yet so harassing will do. Also the team will have time to come and help their team mate. So just keep farming, harass here and there, and play it safe.
Late game
So if the enemy didn't get an oracle in mid or early game. Then they will definitely now. Tell your team to try and focus that person so that you can take em down. If the person that carries the oracle's is a tank then your gonna have to take down the other player first and then focus the tank. Or just get the tank when he's alone. By this time you should at least have your first bloodthirster. Now you should be able to dish out damage to enemies. Only go into teamfights if you need to but focus your efforts on backdooring. The enemy team will try to come back and fight you but you can just stealth and run away. So focus on that. With that you should be able to win.

So yeah this is my build and i hope you guys enjoy playing Twitch. As i said earlier this is my first build ever that I'm putting on Mobafire so just give me suggestions, try out my build, and just have fun with Twitch and do try to follow the build as much as possible. :P But seriously i hope you guys do enjoy playing twitch and you do win because Twitch is a fun character. I thank everyone that has read this guide and i hope that you too will have fun with Twitch. :D