The goal of this build is to minimize the skill required to make teemo work. Teemo's mushrooms are a completely broken ability. In the WORST case scenario, they provide vision. In the best case scenario, they can easily win the entire game for you.

This build is for old goblin techies players.

Your goal is to survive laning phase, farm, and get your items. Don't bother trying to kill unless you know you can in the matchup. Just make sure to get the farm.

Once you're 6+ you're going to start going to nearby objectives and shrooming them before people get there.

Mid Game and Late Game you have a SINGULAR playstyle:

1.) Go to the next objective no more than 4 minutes before it spawns.
2.) Put mushrooms in choke points and where people will path to it
3.) Be safe and stay out of danger
4.) In teamfights, simply throw your shrooms on everybody (so make sure to always have at least 1) and press Q on the auto-attacking target (usually the ADC). Aside that, just ignite a high value target and blow your load.
5.) If neither scenario is occurring, just farm side waves putting 1 shroom on the wave and autoing each melee 1 time and auto + Q on the cannon minion.

In general, if you have more than 1 shroom available, you want to place one in a location where people will walk. Use your brain. If they keep using red trinkets in the same areas and are never getting hit by shrooms there, maybe don't put them there...

The sky's the limit in shroom placement skill. It literally can very easily win games even as high as diamond.