This is a Mainly AS/AD Teemo who changes depending on who you are fighting. You probably won't be almost killing someone with 1 mushroom so if that's what your looking for you might as well leave now. If not, Read on, and Enjoy

I use a 21/0/9 Build taking AP & damage in Offense while increasing my Health and Mana Regen and EXP intake in Utility with a nice little bonus to Monster buff timers.

As you can see I just give myself Armor Pen. Marks, Dodge Seals and Magic Pen. Glyphs with some Flat Health Quints just to keep me alive a bit longer in Teamfights. Feel free to experiment with your runes. Let me know if you find a better set.

[Passive] Camouflage: If Teemo stands still for 2 seconds without taking damage, he becomes stealthed (damage will break this effect). Moving or taking actions will break Teemo out of stealth and give him Element of Surprise, increasing his attack speed by 40% for 3 seconds. This allows for some pretty effective Ganks and some truly amazing getaways. For instance, you're running away from 3 enemies bent on your destruction. You enter a bush and stop, 2 seconds later, you're cloaked and the enemy is running around tearing they're hair out. Nothing is more fun then watching 5 enemy champs walk directly over you with no idea you are there. This also makes ambushing a breeze because you don't need brush to hide in. And you get an attack speed boost!

[Q] Blinding Dart: This is your main survival skill, this will keep those pesky DPSers swinging at air while you melt they're faces off with your poison. I tend to use this as soon as an enemy attacks me, this will keep they're auto attack from hitting you for long enough to get in some damage of your own. A good combo is Blinding Dart then Exhaust right as the blind effect ends. This gives you very minimized for a good 6 seconds which is generally enough time to kill or seriously damage a foe.

[W] Move Quick: A Passive Speed boost for as long as you don't get hit. You can also double the speed boost for 3 seconds! This skill is pretty sweet overall since the speed boost lets you move around the map faster and activating it is great for chasing or running away.
[E] Toxic Shot: This is what makes Teemo so much fun to play. Each time Teemo deals damage to an enemy, he will poison the target, dealing damage on hit and each second for 4 seconds. This will allow you to get kills when your dead, running away or just can't seem to catch that 20 HP Master Yi. It also gives a very nice boost to your overall damage over time. This is very nice early game because many people don't realize just how much damage you are dealing them until it is to late.

[R] Noxious Trap(Mushrooms): Unlike other champion's ults this is not a single target spell or A.O.E explosion. Teemo's ult allows you to drop mushrooms that go invisible after about half a second then stay when you set them until some unfortunate enemy walks over one, it then explodes slowing nearby enemies and Dealing damage over time for 4 seconds. It also provides limited sight as long as the enemy/s are slowed. Traps last 10 minutes. Teemo gains a "stored mushroom" charge every 30 / 26 / 22 seconds with a maximum of three charges. Each cast requires and consumes a charge. Teemo's Noxious Traps can reveal Fog of War much like Sight Wards. Players can also use Teleport on the mushroom. Champions with "Teleport to" skills such as Jax's Leap Strike & Katarina's Shunpo can "Jump" to the mushrooms. One last thing that is amazing fun, Blitzcrank's Rocket Grab & Amumu's Bandage Toss will grab mushrooms if they have not yet become invisible so if you can pop out a perfectly timed mushroom the Blitzcrank will end up pulling a poison bomb back to him!

Now for the actual skill sequence
If your are going to gank or think you are going to be ganked start off with Blinding Dart. If you are taking middle or not expecting to meet up with much aggression then you can start with Toxic Shot but make sure you have Blinding Dart by level 2. I personally take Move Quick at level 4 because it gives me some increased mobility since I generally don't have my boots yet but you can take it earlier or later depending on your own preference. Obviously Max Toxic shot first. Then you can choose to level Blinding Dart or Move Quick from then on depending on the game. Make sure to level your Ult whenever possible.

-I take Ghost and Exhaust. Ghost is a great chasing and escaping tool and Exhaust allows you to survive some of the fights you would normally die in as well as slowing down opponents.

Other Choices:

Heal :If you are feeling nervous about surviving early game then you could take heal just for the HP boost when you really need it.

Flash :Personally I'm not a fan of Flash but I know many other people like it so if you prefer it to Ghost go for it.

Ignite :Again, not a big fan. Ignite seems to be pretty pointless late game. But if you really want those early game kills, I suppose you could take it instead of Exhaust. Just make sure you still have an escape spell such as Ghost/Flash.

Okay, Items at last. I personally start with a Doran's Shield.

You can also start with a Doran's Blade but because I play a very timid Teemo I find the ability to regain health without having to hit minions is easier and overall more effective.

First time you go back to base you should try to have at least enough for your boots, Buy Berzerker's Greaves. If you are having Major problems with Stuns/Slows/Taunts you can take Mercury Treads but you lose the early game attack speed bonus which can be very bad.
If you have enough gold left over start buying Daggers on your way to Malady.

By your next visit to the shop you should try to have enough for Malady and a Vamperic Scepter.

Build your Vamperic Scepter in to a Emblem of Valour as soon as you have the gold for it. Now that you have lifesteal it should be pretty easy to stay in your lane until you have enough gold for your Recurve Bow.
You can even wait until you have enough for the Stark's Fervor too.

Once you've built your Stark's Fervor this build becomes totally customizable depending on which champs you're fighting.
I almost always build a Madred's Bloodrazor next but depending on who you are fighting you can get any of the items I have listed (or others if they work).
If you are fighting a lot of Casters, go for Wit's End & Frozen Hammer.
Lots of Tanks or High life People? Build a Madred's Bloodrazor And watch they're Hit Points drop!
Having trouble with high Armored foes? Grab a Last Whisper.
Enemies running away? Grab a Rylai's Crystal Scepter or a Frozen Hammer and watch them slow down with every hit.
Want more Lifesteal? Go with a Bloodthirster or a Hextech Gunblade.
Tired of that Jax dodging every shot? Grab a Sword of the Divine and use it well!

Now at this point I'm sure you are thinking "Hey Spork? Why don't you grab a Mejai's Soulstealer or Sword of the Occult?" Personally, I find that when I have one of the items with stacks that build off champ kills, I get extremely paranoid and start playing worse because I'm trying to hard to protect my stacks. But feel free to grab either if you feel up to it.

I believe that one of the reasons this build works so well is because it is so diverse. After the Stark's Fervor, You build items depending on who you are fighting instead of following a 6 item build that has you going full AP when you are fighting a team full of tanks with high Magic Resist. This allows you to become the perfect weapon against the champs you are fighting.

Pros

1. Great Ambusher with Camouflage.
2. A good carry with huge damage output late game.
3. The Ability to blind foes can really save lives.
4. Mushrooms make map awareness a breeze.
5. Lots of fun to play.

Cons

1. Very Squishy.
2. Requires a strong early game.
3. No real way to disable casters.
4. An Oracle potion can really ruin your day since mushrooms are now fully visible.

I personally try to stay away from solo lanes as Teemo, at least early game, because he just works so well with tanks. When you start a match, try to lane with the tank, since you are so squishy it's very nice to have someone to look out for you.

Well, I hope you have as much luck with this build as I have, and have fun playing Teemo!


Changelog

10-24-2010 : Wrote Original Build. (Speedy Vampire Teemo)
1-23-2011 : Completely Rewrote & Renamed Build.
1-23-2011 : Slight changes to wording and a few extra lines added in the items section.
4-10-2011 : Covered changes to Move Quick, Small Addition to Noxious Trap section, Changed Seals to Dodge & fixed some grammatical errors.

Thanks for Reading,
Spork