Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
SOLO 1v2: Solo laning with teemo against 2 enemies will reap lots of kills and a tower.
EARLY GAME: Once you arrive at the top lane you will want to go invisible in your defensive bush, or in the lane near your turret. This positioning will give you easy vision of the enemies, and provide quick last hits for the early advantage. During the early lane phase you will use your basic attack to harass the enemies as much as possible without taking damage from minions or the enemies. At level 2 use your blinding dart to attack the physical damage champion. If you don't have a physical damage champion attack the weakest opponent. This will be key to your success in a few levels. Continue harassing until the enemies are about half hp each, keep them at an amount where they won't recall. LEVEL 6 is where the fun starts. Stack 2 mushrooms and go place them in your gank-bush and the defensive bush (See Screenshots for detail). These will give you safety and give you easy kills when your enemies step on them. Now that these safety mushrooms are out put some along side the minion wave DO NOT LET THEM GET HIT BY PASSING MINIONS, this is the biggest mistake Teemo's make, by killing minions with your shrooms early game you sacrifice huge damage that can be used to kill champions. Save your mushrooms for the champions. AN ENEMY HITS YOUR SHROOM This is the ideal lane situation. The enemy will probably get brought to about 300-400 health from half hp (You have been keeping them down I hope..) At this point you can either: Play passively and let them run away and recall or KILL THEM! If their lane partner is too far away from them, or unable to dish out the damage/crowd control to stop you than leap on them. Flash ONLY IF YOU HAVE TO, otherwise you can casually rush at them and shoot a blinding dart, then auto attack them until they die. WORST CASE SCENARIO: Their lane partner acts quickly and counter attacks you, DO NOT PANIC. If you freak out and mess up you WILL die. First use your blinding dart on them and quickly move toward the nearest shroom/turret. (Decide based on their HP and your confidence in killing them) Next either recall OR use your exhaust on them if they hit the shroom. This will significantly increase the damage because of your masteries, continue to blind/auto attack them. Prophit! You are now fed enough for your boots!
MID GAME: Continue to lane and harass the enemies. Last hit like a god with your poison, and place mushrooms! Mushrooms decide the fate of your team's mid game. Use this list to decide where you place your shrooms.
SHROOM PRIORITY LIST:
1. Dragon, Baron and other high value minion camps (Lizard, Golem)
1a. Protective areas to kill tower divers, gankers, and your enemy lane.
2. Highly traveled areas
3. Easily gankable areas
4. Normal creep camps
5. Their nexus?!?!?
LATE GAME: Late game your usefulness decreases with normal AP builds, that is why in my build there is a Madred's and Hextech Gunblade. Use your increased damage to tear their AD carries apart. Teemo is great at shutting down a high damage target like Ashe or Miss Fortune with his Blinding Dart. Use your size to your advantage and sneak through team fights and tear apart the enemy carries.
CONCLUSION: Teemo is great for killing the enemy carries. Good luck have fun.