So hi i wan't to share my build cause i get asked for him once so far and i really like it and i can reverse whole game in it and sadly all of enemy team telling teemo is OP :D HE DOES NOT they just dont know how to counter his mushrooms you can't buy "thousand" wards and geting money and money to keep them on the map and if you soo i gues youre olny support to placing ward so even if you count your mushroom you do whole match 4v4 cause of hard get money to other items for support even oracule elixir is pretty hard to buy and you still can step in mushroom so yea you can counter it but still teemo be here and it's a verry verry big chalenge so if you wish you can try but there is still his E and Q and you hardly counter that (have to use blind and silence at once to counter at last one of them) so yea hardest champ to: Counter, Gank and Try hard to kill if you try hard to kill him prepare yourself to die.

Why Glyph of Scaling Ability Power? cause you're more on late game then on early cause you have Greater Mark of Magic Penetration and that give you some start haras not big but enough to do some damage so in my opinion you got really advantage on 18 level thank to Glyph of Scaling Ability Power then you have Greater Seal of Cooldown Reduction because you need mushrooms everywhere and they can save your live and live of your team mates on hold enemies up cause "toons of damage"
and then you have "recommended" Quintssence. that's on you what you rather have if abbility or penetration or more coldown.

Masteries youre on classic tree you have to do damage. then you should have more recal speed cause if youre alone in a junngle and you know they want you to chase you down this second can save your live! so Improved Recall so its really good choice there then you need speed cause your coldown on moshroom is really low....about 20 seconds? so you need be fast Wanderer is another good choice plus it tune up Ghost and Move Quick passive and active. Perseverance cause you need to stay in jungle and regeneration on Teemo basic regeneration is very low so it will help you get it right a little bit Durability should help regen too a little bit. thats all what i want to write about masteries so far.

you should first learn Toxic Shot cause it is like a small "ignite" and when you devolp it more it will be really harasing and annoying for enemies so you should focus on that.


second skill is Blinding Dart you can save your team mattes thank to this skill or yourself and it's pretty good counter for AD-C like Tryndamere Master Yi and for example Jax you can blind them and kill them cause they can't do you any damage if they dont uses spells so attack speed there or basic attack damage is useless here...(you make them useless) and when you get some AP and max this spell you sen one blind dart for at last quater of their healt.


third skill is Move Quick and it's pretty awesome to run when they seen you placing mushrooms alone or just walking around or if you want to alert them to your mushroom + you're pretty hard gank able. You can even run from singed when he turn on his ultimate if you buy enchant speed on boots youre faster AND I guess it's pretty nice speed ^.^


Finnaly !!! Noxious Trap!!! that's what all full AP teemo is about you can do ton of damage when you acquire Liandry's Torment cause your mushroom slow down and this will double effects of this item you can low down even tank healts pretty good. (DONT BUY RYAL YOU HAVE SLOW ALLREADY AND ON OTHER SPELLS U DONT NEED THAT!!! IT ONLY TAKE YOUR SPACE ... but i give it a try with change of a something but for now i think this build is ultimate as it is)

Ghost - It will help you alot with combination of Move Quick and you run really fast from danger.

Flash - You will need it this will help you get a chance to escape from almost every situations.

Ignite - This will with Toxic Shot do a lot of damage but change it only for Ghost i dont recomend change it for Flash cause a Move Quick is some kind of mini Ghost

Pros

-Late game really strong.
-Hard to gank/counter.
-Can run away from almost everyone.
-Good haras even from start.
-Best "Runner" in a game.





Cons

-Hard to get money on items u have to be patient and hope your team hold it on until you get your items (lategame)
-Really paper.
-You have to know High Trafic Areas.
-If you dont how to play tricky you probably can ruin game everyone.

I will update it guide frequently and repair some dramatic issues so i hope you enjoyed this guide so far and i hope you will visit it again to see my step foward. Thank you.

PS: Please if you downvote let me comment what do u think i should upgrade or change (but have on mind this is just way you should go if you want "edit" this build on your own you can but this is how i think its a best way of ap teemo but final decision is on you youre a player you have your own style and you want to play this build so feel free to testing it in more ways and if you think some combination is better let me know thank u. :) )