Hello,

After some games with teemo i decided to write this build.
Teemo may be played in diffrent ways. AP/AS teemo with on hit effect is most funny way

AD Teemo => NO
Teemo has a short range and his abilities scale with AP.
If you want a ranged AD you better choose another char.

Why AS/AP?
Teemo has a good attack speed. Which make AS items effective.
With malady, he will get more magic penetration wich will allow him to put more magic dommage from poison, abilities and items (malady and Madred's bloodrazor).

Pros
Map control
Nice AOE crowd control
AD carry disable
Huge dommage
Fast


Cons
Very Squishy
Always focused
Brust allies may KS

- Marks combined with sorcerer's shoes and malady grant 24 magic restance reduction, 28.5 magic penetration + 10% from Arcane Knowledge.
- Glyphs and Quintessence grant 42 AP at level 18 (combiened with mastery blast +18AP,mental force + 3 AP and archmage +5% AP and with rabadon effect+30% AP, it gives 81 AP at level 18
-Havoc and executionner add 7.5% dommage
=> MAX magic dommage

- SEALS gives 175 HP at level 18 for survivability

Teemo is squishy. Flash is a must have to get kill or run
Ignite with teemo dommage over time grants a kill on low HP flying enemies
+5AP/+5AD from mastery summoner wrath on ignite cooldown is very usefull early game

Startegy:
- Teemo most important role is warding.
He is fast so he should go and ward with mushrooms all the time.
His team will get map control and he will get free kills and assists while helping team mates escaping or assist in kills.

- Teemo second role is anti AD.
His blind destroy AD carries dps for few seconds while you or your team are attacking or retreating.
Blind + Mushroom slow can turn the battle side

- Teemo can be also played as a fast killer. his stealth and mushroom stealth can allow you to sit and wait for enemies then put all your fire power to kill them fast then run using move fast

Start with a doran blade in order to max dommage early game and farm effectivily.
HP and life steal are needed since teemo is squishy.
At this point your objective is to farm and to harras enemy with poison.
Try to put pressure by keeping poison effect on him which means a hit every 4 sec.
After getting your move fast, two or three level in poison and taking 60% of enemy health by harrassing, try to gank him using blind and ignite

At first back don't buy boots as you already have move quick.
Buy malady or at least 2 daggers.
Malady grants a boost to AS and some usefull 25 AP and 24 Magic dommage
The Magic resistance reduction buff combined to magic penetration runes will ensure max dommage from poison and abilities. you should be able to hit at least twice when harrassing (=12/18 magic resistance reduction)
As soon as you get mushrooms ward and secure your lane from ganks

At second back buy speed boots and nashor tooth or at least stinger.
At this point AS is huge and allow you to put all magic resistance reduction of malady when you attack.
Bonus AP will increase the dommage from poison and abilities.
25% Cooldown (+ 4% from sorcery) alow you to have mushrooms faster.
Get gollem and start warding jungle and ganking.

At third back buy sorcerer's shoes and Rabadon deathcap.
Here starts the AP edge of teemo
You have up to 52.5 magic penetration + 10% and more than 400 AP combined.
You can fully play your role.
Secure fight terrain in team fights by putting mushroom in your way back.
Stay back. when an enemy is hurt go in, get 4 hits and a blind, put a mushroom ignite then go back with move quick.
you should be unreachable and lethal. your mushroom are every where and stupid fleeing enemies will dies trying to escape in the warded jungle.

At fourth back buy Madred's bloodrazor.
This is a very god item for dps.
AS helps putting Malady buff and reaching AS cap with your passive
4% Magic dommage synegize with your 52 magic penetration.
40 AD helps as your AD is low (only 10 bonus AD from doran blade). Stacking health and magic resistance to counter you will be less effective.
25 armor is always welcome at this stage.

Tankiest enemies espacially AD will fear you. just hide and put a mushroom. Slow enemy, blind him when you are in his range, get a kill in 4 sec without loosing too much HP then run with moove quick.

If the game isn't over and you need more survivability get the Ryleys CS.
It increase your magic dommage by 80 AP (around 110AP with bonuses)
It gives a slow with your blind and extra slow to your mushrooms
And 500 MORE HP in addition to the 175 from seals.

But if you want to increase your dommage output go for a lich bane.
It increase your magic dommage by 80 AP (around 110AP with bonuses)
It gives 7% more speed
30 usefull magic resistant (you only have 25 bonus armor and 0 bonus magic resistance)
350 precious mana as your mushroom and blind cooldown is low
and 100% AP bonus (+ more than 500) after using blind or putting a mushroom
speed and brust is very usefull as you are squishy late game. your role is to put fast dommage , leave a msuhroom and run