Hello and welcome to my very first build :)

Teemo, the Swift Scout, is my most favorite champions of all time. If you simply want to annoy the heck out of your enemies and make them rage without saying a word, Teemo's the yordle for you! Honestly, I used to play Teemo as an AD on-hit and quite ironically, I thought his AP side sucked. That was, until I discovered his poison becomes so freaking overpowered with all the AP. It's not surprising to me Riot decided to nerf Teemo's ability power ratio twice (since the Darius patch). Keep in mind AP Teemo acts as a Hybrid (a mixture of AD and AP, or AS and AP), so it's a good idea to focus on AP and AS with a side of CDR.

In here, you'll see my unique build and how it works well compared to other builds.

My Recommended Runes

Greater Quintessence of Ability Power Flat AP - Must have. This helps Teemo with his early-game harassing. Teemo should have 40+ ability power at level one. Talk about that harass before minions even spawn.

Greater Glyph of Scaling Magic Resist Pretty much recommended for any champion. Scales well and helps prevent early-game harassing in case you go mid or bot against Soraka, Sona. etc.

Greater Mark of Magic Penetration Recommended as well. This helps your dart, poison, and mushrooms ignore some of that Magic Resistance they may get.

Greater Seal of Cooldown Reduction I really like this even though I'm not a big fan of CDR on Teemo. Teemo shouldn't have to build an item based on CDR and whatever else that goes along with it. ( Nashor's Tooth, for example) These seals can take that "need" away, giving you less waiting before another dart or Shroom is available.

Other rune choices

Greater Quintessence of Movement Speed Although I recommend getting that +15 AP for early game harassing, only get these if you feel like movement speed suits you better. After all - the faster Teemo is, the harder it is to catch him!

Greater Mark of Armor I do not recommend this, since your Q already saved you lots of damage from that pesky Master Yi. These marks, however, can prevent early game harassing if you're going bot or top and might just save your life!

Offense

Summoner's Wrath - When your Ignite is on CD, you get an instant 5 AP and 5 AD. Teemo benefits from BOTH at the same time. However if you didn't take Ignite or Exhaust, put this point towards your CDR or AS.

Sorcery - I suggest 4 points into this, however it can be interchangeable with Fury

Spellsword - For Teemo, this one point is quite OP. 5% of your AP in extra damage for your basic attacks. That's like extra poison.

Executioner - Increases damage by another 5% when your enemies is below 50% health. Ever had that moment when a champion managed to escape you with less than a bar of health? Well this one point can pretty much ensure that champion is dead. This is excellent with Spellsword . Also helps with last hitting the minions.

Utility

Wanderer - can be interchangeable with Meditation . However you feel like is your style.

Biscuiteer - Solves that lack of health/mana pots problem early game. You should be able to send your enemies back to base before you do with your poison harass.

Defense (Optional)

If you wish to use those last 9 points into the Defense tree instead of the Utility tree for more sustain, I would suggest:

Durability - 4 points - More health, after all Teemo IS squishy.

Hardiness - Interchangeable with Resistance

Relentless - 7.5% reduced effectiveness of slows. Faster Teemo = Safe Teemo = Happy Teemo

Skill Order

Noxious Trap > Toxic Shot > Blinding Dart > Move Quick

Camouflage Passive - Camouflage - How you use your passive determines whether you're a good Teemo or not. There are so many ways and benefits of using this passive. You can use your passive as a "live" ward, wait for an enemy to walk over your Noxious Trap that's near you then attack that enemy, or even for the attack speed bonus.

Q - Blinding Dart - This is what you level up after Toxic Shot. You usually don't rely on this early game however this dart will determine life or death for your little Teemo. By the time you get Lich Bane, this Dart will be your main ability to use in order to proc that Lich Bane's passive.

W - Move Quick - Your escape. Your chase. You use this pretty much to escape, chase, or simply get to somewhere fast. This ability also will determine life or death for you.

E - Your passive and early game harass. This is the heart and gold of AP Teemo. Even after two nerfs, the AP still scales very well.

R - My god. The damage, slow, and map control on this thing is INSANE. Scratch off that comment I said about Toxic Shot being the heart and gold. THIS is the heart and gold of AP Teemo. There are so many uses to this.

Uses
-Map Control
-A way to escape
-Plant on top of your target if you can to proc more damage
-Can clear big minion waves
-Can get anywhere on map if you bring Teleport with you

Recommended Spells

Flash - My primary spell for Teemo and pretty much any champion I play. This spell is amazing, even after that huge distance nerf on it a long time ago. The spell can both save your life numerous times and catch up to that pesky Champion that got away from you.

Ignite - Pretty much recommended for Teemo and most of the other champions. This with Toxic Shot and Liandry's Torment spells INSANE DoT (Damage over Time). It also reduces healing which can counter certain champions such as Dr. Mundo and Master Yi or any champion with the Heal spell.


Other Alternatives

Ghost - You can replace Flash with this if you're not that skilled with Flash yet or haven't reached the level requirement for it. You can also replace Ignite with this to ensure you won't get ganked or chased down, but I only suggest that if you want to play super-safe Teemo.

Exhaust - This can slow down an enemy you're after and/or to reduce the AS on the ADC you're after. Exhaust a carry before a team fight occurs and it pretty much marks a big "Come get me" sign on that person. It's quite funny watching your team go all over that helpless person ;)

Teleport - Pretty useful. You can get somewhere quick with this thing, and note you can teleport to your mushrooms.

Cleanse - Only take this if your team has really strong CC. Amumu or Nunu & Willump for example.

Heal + Barrier - Helps you survive since you're so squishy and focused. Heal also heals your allies in case they're about to die. A lone Teemo is no safe Teemo after all!


NOT Recommended

Revive - People only take this if they plan on dying a lot, yet it still doesn't really help them get back on track, just more feeding.

Clarity - You're not Karthus. You already have Lich Bane for extra mana.

Clairvoyance - You do NOT need this useless spell. It's better off on a Soraka or Alistar. You can plant dozens of mushrooms that last up to 10 minutes instead.

Surge - No longer available.

Promote - No longer available.

This is pretty much what your build should look like.
Starting Items

Amplifying Tome + Health Potion - Helps that early-game harass that hopefully can get your team an easy kill. Try and get a Boots and a Sheen on your first trip back to base.


Early Game

Sorcerer's Shoes + Lich Bane + Recurve Bow - This is where you should start getting fed and getting that map control. Once you get these items, you should be able to do some good damage. Lich Bane should be your main item by now. This one item gives you extra damage, extra mana, extra movement speed, and that "double" Blinding Dart. Pretty much covers everything Teemo needs.


Mid Game

Runaan's Hurricane + Rabadon's Deathcap - This is where your enemies will focus you hard simply because you've gone out of control. Mushrooms are all over the place, you can 1vs1 a fed Ashe or Master Yi. Runaan's Hurricane helps clear minion waves and dominate in those early teamfights as it DOES apply on-hit effects. Yay for more poison! Rabadon's Deathcap obviously give you that INSANE damage.

*A couple of people suggest getting Malady, Wit's End, or Nashor's Tooth instead of Runann's Hurricane. I personally disagree with this as, yes it does offer survivability, it doesn't cover everything Teemo needs. 70% attack speed from Runaan's Hurricane covers Teemo's AS need and helps him clear those minion waves which leads to an easy Rabadon's Deathcap. Only get these if you like to get risky.


Late Game

Liandry's Torment + Frozen Mallet - By the end of this build you pretty much can 3-hit any champion unless they're a pure tank, such as Dr. Mundo. Frozen Mallet has great health, some AD which does help AP Teemo, and will prevent anyone from escaping and is GREAT for kiting. Liandry's Torment I don't even have to explain this.. The 5% current health burn plus your Toxic Shot and Spellsword pretty much tells your enemy to dig their grave and surrender. Note that Liandry's Torment only procs on Teemo's Toxic Shot after the last tic of the last stack of poison, which helps clean that person up if he escapes with less than a bar of health. Thanks to Carlituz for clearing that up.

*Originally I placed Void Staff as the last item instead of Frozen Mallet but after testing Frozen Mallet, I learned that it is indeed better for Teemo late game. Thanks to Tuatha182 for the suggestion.


Other good items

Malady - This item is great for you if you want more damage off your poison. It gives AS, AP, and reduces their magic resistance. Replace this with Runaan's Hurricane.

Wit's End - It gives decent AS and helps you survive more. Only get this if your enemy team has a hyper-fed AP carry like Katarina or 2+ AP carries. Replace this with Runaan's Hurricane.

Nashor's Tooth- This item gives decent AS, AP, and 10 mana regeneration. The main stat is the CDR though. Only get this if you rely on planting mushrooms all over the map or want strong map control. Replace this with Runann's Hurricane.

Void Staff - If you're not a good kiter and want more damage, get this item. This helps penetrate that pesky Magic Resist and gives decent AP. Replace this with Frozen Mallet.

Guardian Angel - This has good armor and magic resistance. The passive is really great, and can change a teamfight around. Only get this if the game is taking too long to the point where your death timer is around 50-60 seconds. Replace with Frozen Mallet or Runann's Hurricane.

Rylai's Crystal Scepter - Not really recommended but some Teemo players do get this. It has good AP, health and the passive procs Teemo's Blinding Dart and Noxious Trap. Replace with Frozen Mallet.

Here are some pros and cons of playing AP Teemo.

Pros

-Extremely easy
-Very mobile/fast
-Can be nearly impossible to catch if played correctly
-Mushrooms give major map control if placed correctly
-Can kill someone in just 3-5 hits
-Counters most AD carries
-Ganks pretty well
-Very flexible with lane positions
-Make enemies rage
-Cutest champion of ALL TIME

Cons

-Easily countered
-Always focused
-Squishy
-Has to stay a little outside teamfights in order to prevent being focused so early

When to Play

-Your team has no counters to an ADC
-Your team lacks map control
-Your team needs a mid
-Your team needs an "ADC"
-Your team needs a support
-Your team needs a solo top
-Enemy team has lack of CC
-Enemy team has a Master Yi
-Enemy team lacks mobility
-Enemy team is very squishy
-Enemy team begs to be annoyed


When NOT to Play
-Enemy team has tons of CC
-Enemy team is very tanky
-Enemy team has lots of burst damage
-Enemy team has Akali or Yorick
-Your team needs a jungler

You're just dying to make the other team rage, aren't you? Stop reading this and go make a new game, will you?

Best of luck and please comment, some feedback would be appreciated :)

12/30/12 - Replaced Void Staff with Frozen Mallet. Added more information between the two.

12/31/12 - Added optional items and their uses under the Items section.

1/1/13 - Minor typo fixes.