Remember: When you lock teemo in, make sure that it is night, and that you are riding a black unicorn down the side of an erupting volcano.
Then fill a chalice with the blood and tears of your enemies, preferably without salt. Then draw Satan's symbol while chanting that size doesn't mean everything.
Proceed to enslave a dragon and make him give you a mermaid before sending him to the sun with a nuclear missile. Follow the instructions for the next step carefully.
Take the mermaid. And force her to sleep with medicine. Then put her in a pool so she doesn't die.
For thirteen days, makes her wake up out of the water, letting her think she will never find water again, and force her to sleep right when she walks close to the pool, just so she only gets a glimpse of it.
On the thirteenth day, make sure it is a full moon. That's when the mermaid will get desperate, and unleash her curse.
Right as she unleashes her curse of hate, kill her with a silver shot in the abdomen, but make sure you keep her mouth open so the evil spirits can communicate with our dimension through her mouth.
You have to be quick now. Put her in the middle of the Satan's symbol you drew 13 days earlier, throw a drop of the liquid of the chalice at every corner of the symbol, drink about the 1/4 of it, then throw the rest at the place you shot the mermaid, so it spreads evenly around her.
This is when the summoning will begin. Of all the evil spirits, the worst will come out.
Teemo.
The death ray coming out of it will kill every alive being within ten kilometers of Teemo, but it won't kill you, since you have drunk from the liquid which was the source of it's dawn in our multiverse.
With a burst of new-born flame, it will draw the space-time continuum (and you) towards him. Luckily for you, the sun distorts the space-time continuum around it.
If you have calculated everything correctly, this is the point when the missile will reach the sun, just before Teemo's wrath penetrates the sun's space-time continuum distortion.
The nuclear missile and the dragon will transform into a massive super-nova, turning the sun into a black hole. Hopefully, the supernova will be drained by the black hole and nullified by teemo's anti-matter radiation, letting you survive it.
The laws of physics will soon tear apart. You and Teemo will be sucked in the black whole, and appear in another universe, but with swapped bodies. You have a couple seconds to mock It, now in a weak mortal flesh.
Now quick, before the white whole which brought you to this universe closes, use the last of the power of the liquid you drunk to transfer yourself back to your universe.
Using the awesome new powers of its body, return the world 42 days earlier.
Congrats! You banished Teemo from your universe forever, destroyed it, and now you live in it's impenetrable body of pure evil! Have fun!