With this set of runes you are optimized for the best magic damage on hit, with increased attackspeed and cooldowns.

Why cooldowns? Placing mushrooms faster improves your team's map awareness - REMEMBER: mushrooms are primarly just like sightwards, only secoundarily like weapons.

know when and where to place them. (ex. baron, river, escape routes and behind your towers to incapacitate and screw up tower divers)

Items. With huge attackspeed comes a question: shall i raise it till cap or get some attackdamage?
Answer is: attackspeed with on hit effects. To do so, i pick these items to be the best of best for on hit dmg and mushroom spam teemo.

in teamwork aspects: focus the enemy carriers and blind their auto attackers.
with this setup, you can even make a tank with not much magic resist bend on his knees.

Pros: high speed damage and good gold-item relation. (aka not much gold spend for a great item and dmg output)
Cons: nearly no survivability makes you a target easily. be wise picking where u stand when attacking.