Teemo is supposed to bring map control as well as to do alot of damage. Since you as top already got a ad carry your build will help your team take down the enemy team offtank and tank. The most important to know when playing teemo is when to fight and when to off. Keep spamming your ult to get vision over the map especially in bushes, near baron and need the dragon. Do not engage a teamfight ever. Stay in the background and focus whoever is the biggest threat to your ad and ap carries. If you keep them alive they will burst the enemy carries at no time. Remember that taking down a enemy carry might seem easy but you this is not worth it if you can't keep your own carries alive at the same time.

Early game is really good for teemo especially if the enemy is a ad melee. If possible be agressive as hell but don't push your lane. With your runes you will be able to deny your opponent alot of creeps. Placing shrooms in the river will make you hard as hell to gank. Remember that gettiing alot of gold is your main goal so don't risk cs roaming too much.

The runes is for an early game advantage only. The flat damage will give poke as well as help you lasthit. The armor will help you stay alive in top. If the enemy at top is ap get mr instead. The ap is only to buff your toxic shots poke damage. The blinding dart is not for damage at all. Don,t ever use blinding darts for damage it's a waste and a auto will deal more damage overall.

At top all you do is to poke and farm so dorans is a good start since you should keep a the distance to your opponent. Afterwards boots are really important for so many reasons. Phage will help you stay alive and also give you a nice slow on auto chance. Next thing you will need is damage so you will build Bloodrazor starting with damage and then attackspped. Afterwards Frozenmallet is important. Getting that will keep the enemy at distance. This also secure the kill if they try to run away. The Black Cleaver is simply for breaking down the tanks and the attackspeed benefit the passive of the Bloodrazor. Bloodthirster for extreme damage as well as keeping you at high health. Well ga speak for itself.

Notice: As teemo you might seem like a target for assasins but really you are not. Notice that you will have almost 190 armor with the full build.

Last but not least. Don't ever build malady or nashors tooth. In my opinion one of the reasons teemo is underestimated is this that many is building this weak hybrid build. GO for eigher ad or ap teemo not hybrid.