Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This build relies heavily on a high attack speed and on hit effects. The malady, black cleaver and madred's bloodrazer all work really well together and well ensure you will be taking down your enemies left and right. Flash is always nice to have to get out of a tight spot, then use move quick to get out. I pick exhaust for the other spell b/c since this build doesnt incorporate a slow into the item build, exhaust will cover that for you, and allow you to have your opponent blinded almost the entire time you fight with an exhaust/blinding dart combo.
For items, start with a vampiric scepter, it should be very easy to keep your health up with it and is one of the parts for the first item you should build, Malady. After Malady, grab Beserker's greaves. The rest of your item build should follow exactly as shown, next is madreds, then phantom, black cleaver, and if you find yourself with gold to spend, grab an infinity edge for your last item. I have won so many team fights with this build and got triple and quad kills because I just blow through my opponents health.
Oh, and if you are wondering about why mana regen instead of attack speed runes, with this build you will be pushing close to top attack speed (2.5 attacks per second) and there is no need to go over, however I have always found that teemo, especially with him laying mushrooms everywhere, has a bit of a mana shortage problem, and these runes help tremendously.