First of all, please add coding to your guide, it will improve it tenfold and make it infinitely easier to read and understand. Right now it's just walls of text and it takes people twice as long to find pertinent information this way. As for AP teemo in general, I'm not the biggest fan because I think it really only affects his DoT and shrooms which are a lot of luck anyway. He just simply can't compete with burst casters and DPS, he falls short in both categories when built this way. That being said, if you do decide to build him this way, you need Rabadon's Deathcap ASAP, before your Lich Bane definitely, and maybe before Rylai's Crystal Scepter if you're farming well. Lich bane just doesn't do that much until you build astrong base of AP, so always build it AFTER your big AP purchases. Also you don't need 20 flat mpen from runes, it's just not necessary and you'll do better building a Void Staff late game when enemies stack MR, but before that you'll benefit much more from 3x Greater Quintessence of Ability Power and 9x Greater Glyph of Scaling Ability Power.