This build is a build wich gives a very good combination of items and give a gameplay for all the skilled and unskilled players.
I am not English so I am sorry for my bad English along the guide.
This guide gives to options of two different tipes of twitch gameplay.
In one gameplay you gank like a jungler( you must be always ganking),
In the other you do a normal bottom dps game wich consists in farm farm farm farm......
My item choices are a bit bizarre but along the guide i will explain the porpuse of them.
In my build the items i choose are not compulsory you should pick too counter items.

In my Twitch gameplay I have two options:I try to finish the game earlier what is more risky or i try a safe late game.

The two options are good but i prefer the early game win.

In the early game win i play a ganky twitch.
Always after the jungle cover i go gank mid with my teamate alreadt in mid for the enemy "midder" to think that im coming to my lane.

In my gameplay twitch ganks a lot just like the jungler to a more effective teamplay.

i said that it is risky because ambush in the beginning has a very bad and shor time so the gank can not be effective and you loose xp, gold, and because of that you can became under leveled.

In my items choice a like to start with tiamatbecause it is very cheep and it gaves great damage, health regen, mana regen and it has a splash passive wich combined with twitch ultimate spray and pray does a huge aoe splash damage wich can be very usefull in teamfights.

I also buy boost of mobility for a better chase and scape.

My choice of the item starks fervor is very good combined with tiamat because of the life steal you receive of the damage of tiamat and because of the great health regen combination wich gives you a great survival.

Spirits visage and bloodthirster are mandatory items because of the health of the spirits visage and magic resist to a better survival because twitch is squichy combined with the passive to a better lifesteal and health regen of starks fervor and bloodthirster.

Infinity edge is an optional item such as black cleaver, madress bloodrazor , warmogs armor and guardian angel.

I also think that the best starting item for twitch is dorans shield because it gives more health points than dorans blad and it makes twitch a better survival because the health regen is very good and because of the armor twitch takes less damage and in dorans blade the lifesteal is very low so it is useless and the damage is alright but comparing with dorans shield dorans shield sure has more qualities.So i have changed it.

About the boots i think that both boots are very execelent choices for twitch so it is up to you, if you want to have a better early atack speed go for berseker greaves but if you want to have a good "escape and chase" gameplay you choose the boots of mobility.
In my opinion i prefer the boots of mobility because i get atack speed from ambush so the berseker greaves atack speed unnecessary.

The late game win gameplay is the most boring twitch gameplay for me because the only thing you do is farm, farm, go back, farm, farm...

In my opinion its a bad choice for gameplay because it makes you no diference from the other ad range in the lane so is just a matter of luck, skill or farm to have an advantage from the other ad range. So this gameplay wouldnt be fair for the unskilled player or less rating players.

But to the more skilled players a give this optional items for a twitch dps critic ranked play.

The twitch jungle is not very used but it is possible(for the ones who dont know).
It starts with cloth armor, in golem(blue buff) and with expunge for the ones who dont have many runes i recommend to have a pull from the teammates.

The jungle route is: golem(blue buff), wolfs, wraiths, gank mid, golems, gank bottom, recall, go lizard(red buf), gank top and then you gank who ever you need.

The optional safe route is: golems, wolfs, wraiths, recall, blue, lizard,

My main summoners spells for "not jungle" twitch are flash and ignite but you can choose between that and exaus and ghost, flash and ghost, exaust and flash, ghost and ignite and exaust and ignite.

For jungle I use flash and smite but you can use ghost and smite depending on your gameplay.

Pros: this build gives a very good aoe splash damage wich is very usefull in teamfights combind with sparay and pray, it is very good for survival,gives a good damage such as life steal and atack speed and a litle resistance to magic damage wich is usefull becausecmages deal a lot of damage.
Cons:Twitch is still squichy with the hp and magic resistance of the spirits visage, if the enemy team gets a vision ward or oracle the twitch gameplay can be ruined so, the champion who posseses the oracle must be killed instantly, if something goes wrong in the first gank in mid( he dies or the champion has a ward so it plays safe) twitch loses a lot of xp wich can make him underlevel for some time.

For runes I prefer armor penetration and critical chance for a good early damage, but if you want you can only buy critical chance runes or just buy armor penetration.
In fact only armor penetration is the best coice because in m item builder i dont put many critic items (only infinity edge and it is a optional item).

This build has a average team work the only support item is starks fervor wich reduces the armor of the enemy champions.
If youchoosethe boots of mobility you will have a more active gameplay and with ambush you will be invisible in a great more area like a movable ward.

To farm you MUST only last hit,use expunge if the minions are in the tower,you can hit only once every minon in the lane and expunge when they are with low health points.
Try to stand in the back of the enemy minion wave to provoque "fear"(only do it when you are feeded).
Try to kill as much minions as you can to win extra gold for more items.

For masteries i use 21-0-9 but if you want to play a more defensive twitch gameplay you should do 0-21-9 wich is a good option because twitch has enough damage by himself so he doesnt need more damage but that depends on your playstile.

ALL: Grynnt
I hope you engoy my guide :)