The twisted Treeline is a map in which I thnk is perfect for AP teemo, because of the various entrences that are narrow and in perfect shroom range. Many people think that AP teemo is not as good as AD and I beg to differ! you can easily win games in which you shroom the area by red and go invis when you know someone is coming, they step on a shroom, then another one you pop out blind, auto poison them, ignite GG FOR THEM. from then on you can push with your team because now they have two or one person (if your lucky enough to catch two with your team) to push towers.

Pros
-fun to play
-very satisfying killing someone by shrooms
-complete control of jungle
-personal ward for team (saves money)
-bait master (Vayne chases with low health you also have low health, you run blind, ignite GG)
-Alot of burst on squishies with blind shot and Lich Bane.
-Can shut down auto attack champs

Cons
-Out auto attacked by AD Teemo
-Takes a while to get used to getting out of lane and spending time shrooming forrests
-Squishie
-Requires alot of farm or kills to get items (LAST HIT, LAST HIT, LAST HIT!)( When shrooming push the lane by auto attacking creeps then shroom the jngle and be back before they get hits on your tower)

Runes are fairly standard with only a couple of things to mention.
-The reason I take CDR seals is because you always want to be spamming those shrooms and blinding dart, works greatn with Nashors Tooth and if you can get Green buff for even more CDR.
-Fortitude Quintences is to counter teemo's squishiness.

Now for the fun and where everyone has their own opinion :)
Now for my opinion in Items goes as follows.
-Dorans ring is a must start out for me. With this you get the HP the AP and the mana regen. this gives you the mana to be pulling of those Blinding dart harrass if there to far away for your auto attacks.
-Sorc boots for the magic pen that works with your marks and makes your shrooms hit even harder.
-Malady is a great starting item, because it works so great with teemos poison that it makes your auto-attacks strong and gives the much needed attack speed.
-Nashors Tooth gives you AP, attack speed and CDR everything AP teemo needs, this makes your malady hit harder and makes your auto attacks again viable.
-Now that you can auto attack time for your big item RABADON'S DEATHCAP, this makes your shrooms damage go through the ROOF! your opponents will fear the jungle once you get this item.
- To complement your Rabadons of course is Lich Bane because thet every 5 seconds or so you can Lich Bane auto attack AND IT HITS HARD makes their HP disappear.

HEXTECH or DEFENSIVE ITEM?
Now if you gotten this far you can choose.
Am I destroying these guys so hard that I wanna make them cry?
-Hextech Gunblade, Spell Vamp, AD for auto attacks, Lifesteal, and AP. Nuff said.
Hmm.. Hard game might need to beef me up a little,I already do enought damage!
-Banshees Veil usually or if they dont have any AP then get a Armor item such as sunfire cape, thornmail etc.

EARLY GAME
-Farm, farm, Harrass, farm. this should be what your doing till level 6. Remember to bait alot if your skilled enough to do it and you know its safe. (keep in mind what summoners spells they used and which ones they have at their disposal.)
MID GAME
-shroom, shroom, gank, shroom. The next chapter is completely dedicated to shrooming effectvely so just remember to shroom whenever you can (never have 3 shrooms available always have the CD for shrooms up so you can maximize the amount of shrooms in the map.
LATE GAME
-Push,Gank, Shroom,Push. This is the part when you need to focus on zoning your opponents to their base or the lanes. PUNISH PEOPLE WHO FACECHECK BUSHES OR GO INTO "YOUR" JUNGLE!

UNDER CONSTRUCTION
Showing a Map of TT and showing all the key shroom spots.

For now just know. ALL ENTRANCES and the whole botomm jungle and shroom the dragon and the two buffs on the top jungle for sight.

Just so you know this guide is new and in under construction! Pictures, editing,and videos will be added.

Firstly I thank you all for taking time and reading my guide.
AP teemo has always been a favorite of mine and with a 80% win rate on TT I must be doing something right xD

Gl and Hf!