Hi Mobafire. I am going to show you how to build Teemo as an on-hit champion. I believe this is the best way to use utilize his skills.



Some general info about Teemo:
Upon selection
"Captain Teemo on duty."
Movement/attacking
"Hut two three four."
"I'll scout ahead!"
"On my way."
"Swiftly!"
"That's gotta sting."
"Yes sir!"
"Armed and ready."
"Reporting in."
Taunt
"Never underestimate the power of the Scout's code."
Joke
"Size doesn't mean everything."

The build says that Teemo has 130% AS. After building the items, your AS floats around 2, with the help of {{Camouflage]].

PROS
Amazing on-hit damage
Fast getaway when ghost and move quick are used together
Quick attack speed
Wards the map
Potential to be a good rice farmer


CONS
Frequently focused (For some reason everyone wants to kill him..maybe it's the shrooms)
Ultimate can be countered with Oracle's Elixer

Ghost and Flash are my two summoner spells. Ghost, along with your skill Move Quick can be very effective while chasing and escaping. You will be fast. Flash to catch up with opponents. You can also place Noxious Trap at a turn when escaping and then flash though a wall to guarantee a safe getaway.

Other viable options include Ignite, Cleanse, Flash and Teleport.
Ignite, combined with your poison, can score you a lot of kills.
Cleanse is also a good choice. If you are focused and someone stuns/slows/etc. you, you're probably going to die. Use cleanse, activate Move Quick, and get out.
Exhaust will help you chase down enemies. Combined with your high attack speed, you will get more hits in.
Teleport is decent for getting back in your lane and for ganking.

I choose to use Greater Seal of Magic Penetration, Greater Glyph of Magic Penetration, and Greater Quintessence of Magic Penetration for increased magic penetration.

I go with Greater Seal of Magic Resist for magic resistance. The items you buy do not give too much, so this will help a bit.

I increase my Toxic Shot first to do some poison damage. Next, go with Blinding Dart. This isn't really a skill that is used for damage, but can be very useful in team fights. You can use it to blind opponents and harass early game if you want. Next, Move Quick will help you...well, move quick. Next I want to work on maxing out Toxic Shot to really get that on-hit damage. Depending on the current situation after that, you can decide if you want to blind people for more damage and a longer duration, or if you want to move faster.

Your ultimate is awesome. Start placing shrooms as soon as you get three stacks after level 6. You won't be at your full potential if you keep forgetting to place them. Your team will be mad, too. There is a very very short CDR, so you won't have to worry about that. Place them strategically in places that enemies are likely to come out of, such as those two bushes surrounding the middle lane. Other VERY IMPORTANT places include Dragon and Baron Nashor. Make sure to place them around the area (In a circle) so that you have full vision of the area, not just the entrance.

The items I build may not seem like the typical AD/AP build for Teemo. I believe Teemo was made to be great when building On-Hit. 


I start out with Doran's Blade. I like this item. You get health, damage, and a little bit of life steal. That's a good start. Buying Doran's Shield and a Health Potion also works if you want to be a little stronger defensively.


Next, get Boots and build them into Mercury's Treads. The reason for Mercury's Treads is that if you get focused (which you probably will), the effects will wear off quickly. Then run away.


After that, I buy TWO Daggers. So Dagger Dagger. You will turn these two into a Malady. The magic damage will do some nice on-hit damage. It also reduces the enemy's magic resistance. Oh wait, you also have magic penetration. KILL KILL KILL


Then, get a Recurve Bow and build that into a Wit's End. Aside from the cool color, Wit's End will give you good magic damage and magic resistance. You should also kill the Lizard Elder for more on-hit damage.


Next. Madred's Bloodrazor. Even the name sounds terrifying. Well, sort of. Build another Recurve Bow first for the attack damage, or if you want to kill some monsters and get more armor, get Madred's Razors. Either way, you still own. At this point, you can also sell your Doran's Blade so you don't have to get Pickaxe and Madred's Bloodrazor at one time. 


Get Phage. Build it into Frozen Mallet. Your Attack Speed is now around 2. If you slow them, you get more hits and they will cry.


It works well.


Other good choices to substitute Banshee's Veil are Black Cleaver, Guardian Angel, and possibly Sword of the Divine. However, I don't really suggest you get the sword because it will waste some of the extra attack speed from your passive. But if you really want to, go ahead. 

Guardian Angel is probably the best choice here because of the extra health/defense I get. Many people believe that more damage is necessary to tear enemies apart. But you already do that. Guardian Angel will give you a lot more survivability at the cost of damage.
I would suggest using this if their team is not too AP oriented.

If only you were farming rice.
Now, it may seem like Teemo does more damage to single targets than many at once. Look at your skills. Blinding Dart, No. Toxic Shot, No. Move Quick, of course! Moving fast lets you farm enemies very efficiently! Just kidding.


You're going to want to use Noxious Trap. Run into the mob of minions and place a shroom. After a couple of seconds, it will detonate, dealing damage to many of them. However, don't forget to use them as wards also! If you only utilize your ultimate for farming, you're not going to be that useful.

A Stealthy Start is a Healthy Start
This strategy tends to score me first bloods ALOT versus weaker players. Start the game going mid, while activating your passive around the center of the map. Have a teammate hide in the brush. Enemies tend to move up a bit further at the beginning of the game to see their opponent. Use this chance to attack your opponent. If your opponent gets away, no big deal.

If you're against an enemy without a lot of AOE attacks, feel free to slow them with Noxious Trap and then wait two seconds in brush to become invisible.

Teleport Required
Place Noxious Trap around your enemy's area when you are ready to gank. Teleport in and get the kill. Your enemy may not have quick enough reactions to run, and will be slowed by the shrooms.

I will do my best to update strategies frequently and post screenshots after games.

-Utilize Camouflage
-Don't stop placing Noxious Trap
-Use Move Quick with Ghost to be fast
-Kill Everything that moves



Thank you for reading! This is my first guide, and I will try to improve it as much as possible over time.