In this build, I will be introducing a different style of gameplay for teemo. It synergizes very well with his skills and is more useful to teamplay. Its Teemo-free week and I see alot of people failing with teemo. Teemo is one of my mains and I believe that this teemo build is truly the best.

Pros
hits hard and fast, like a G6
able to survive in teamfights
good farming
easy to deal huge damage, early on

Cons
No massive shroom damage

I go with...
Magic Pen Marks because we'll be dealing a ****load of magic dmg

Mana Regen Seals because ur teemo, u wanna be able to spam and have good mana regen, feel free to use flat mana regen seals instead of the per level ones

Cooldown Glyphs because u want to be able to spam ur shrooms

Health quints because ur kinda squishy early game, lets fix that

For masteries, I sometimes go with a 9-0-21 build. This can work pretty efficiently.
however...
a 21-0-9 build is JUST as effective.

So here is how teemo's gameplay changes and the explanation to the itembuild and how it makes teemo effective. By no means are the items in strict order, only suggested and based on an ideal typical game. Components can be bought earlier to help with gameplay.

Start with a long sword and pots so you can last hit easier. Basic Madreds is awesome for farming up/last hitting. then, work on malady, which is cheap, has cheap components.

The two CORE items of this build are...


Malady- To take away magic res. and deal more damage

Madreds- To deal a ****load more dmg, getting the basic madreds also helps farming early-mid game.

The other items are...
Boots- You can get whatever boots you please! I usually go with merc treads on the safe side, but beserker greaves, ionian boots all work very well with teemo.

Frozen Mallet- More survivability and good chasing/escaping tool. You can get a phage during mid game if you need more health earlier.

Wits End- kinda situational, good item, synergizes with the build.

Last item- UP to you, and situational.
Recommended/Optional Last items in order are...
Banshees Veil-more MR, block a spell
Triforce- if u decide not to get frozen mallet
Zhonya's- Survive **** like jesus and more AP&armor.
Void Staff- More magic pen, if they are stacking MR.
Anything you feel is needed, depending on the game.

Skills Explained

Getting toxic shot is very good for level one.
Blind shot is probbaly a must on teemo to prevent him from dying.
Quick move's recent patch change has made teemo even better, get this for an early "boots" buff and be able to escape from fights easier.
Shrooms- SPAM SPAM SPAM

The reason why this teemo hits hard is due to the similarity in the items.
1. Attack Speed
2. Magic Damage

Teemo's skill, toxic shot is a GREAT skill that makes teemo so great. Magic Damage= (Passive): 9 / 18 / 27 / 36 / 45 (+14% of ability power) magic damage on hit and 6 / 12 / 18 / 24 / 30 (+14% of ability power) each second for 4 seconds.

Malady- 50 Attack Speed, 25 AP. 20 magic Damage and remove MR.
Madreds- 40 Attack speed, 30 Attck, 25 armor, deals Magic Damage equal to 4% of the target's maximum Health
Wits End- 40 Attack Speed, 30 MR, remove up to 42 mana from the target and deal additional damage equal to the amount of mana removed.

SOoooo.... basically we get a ****load of Attack speed from these items.

With these items, you have teemo dealing a ****load of damage EACH shot. Lets estimate some numbers here...
His normal physical attack (lets say... 100 as an estimate)
Poison - 45 + 30 at level 5
Malady- 20
Madreds- Lets say.... 40 for a champ around 1000hp (trololol who woud have 1khp late game?)
Wits End- 42
100+45+30+20+40+42=272 damage EACH shot
and remember, Madreds is only an estimate for a 1khp Champ. By late game, you will be dealing much much more damage than that. As well, your poison will also do lots of damage over time that is not counted in here.
You have alot of Attack Speed, dealing.. lets estimate 300damage each shot. How wonderful is that? As well you have good synergy effects from malady.

Sword of Divine may also be a good item on teemo, but I opt for either more survivability, or more AP as my last item. Seeing as how teemo does not do much physical damage, i do not find piercing through armor a big deal.

This build may only be as effective on teemo(and probably kogmaw) due to his poison. Other builds say build AD, build AP, build hybrid. But this is none of those three. This is a build that focuses on item effects, teemo's poison, and bringing those two together with attack speed.

For those of you that do not know how to play teemo effectively or would like to improve, here is a quick tutorial.

Early Game: Get toxic shot, and make sure u last hit creeps, its pretty easy to last hit creeps with toxic shot. If people try to farm, especially melee range guys, hit them a few times with ur normal attack and watch that HP drop. DO NOT harasss with your blind shot. Your normal attack deals way more damage and you save your mana. When do you use your blind shot? When engaging in fights where they are going to attack you. When engaging, blind shot then normal attack a few times. By then, you will either be winning or losing that fight. if you are winning, keep hitting, if losing, then start kiting (Learn to kite!) and then wait for ur blind to finish cooldown then engage again. If anything, quick move to escape/finish him off. If you get tower dived, a good thing to remember is blind can save your life or take down someone with you.

Mid Game:
Your early game ends when you are level 6. By now, you should be spamming shrooms all over the map, harrassing/catching the enemy jungler/gankers, and ganking yourself. teemo is a great ganker due to his movement speed. Shroom placement is very important. They can eat away at enemie's health before even engaging. Start shrooming in entrances/bushes/important spots(dragon) along the river. Then as the game progresses, begin to either shroom in their jungle, or your own jungle.

Late Game:
Team fight time! Make sure you are not being targetted by enemy champs, even with frozen mallet you are pretty squishy. If they are targetting you, blind them and attack them, or quick move/flash out of the way so they dont attack you and they die. Shrooming may be just as important in late game. Dont forget to shroom. If you have 3 shrooms in ur bag, you are not shrooming enough. If anything, grab a quick blue buff and go into gardening mode as you spam shrooms.

I find this build to be the most effective and most helpful to the team. Your attacks do a lot of damage and if you know how to fight effectively with teemo, you can get a lot of kills, assists, and deal a lot of damage. You will be hitting fast, like a G6, survive with your flash, quick move, and blind, like Jesus.

Thanks for reading my guide, I hope you will try it out, it truly is a great build, used by high elo players as well.
Feel free to comment/vote.