The ap shown by the build is incorrect, it does not account for the passive of archangles. you will have an additional 549.12 ap, giving you a total of 1022.28, which with teemo's 80% ap ratio on his ult his shrooms will do 1418 damage, which, when they are EVERYWHERE, and invisible, will be quite a problem, especially ignoreing 40% of your magic res. you have almost complete bush control, and oracles don't work if you place the shrooms on the edges of the bushes

You can replace one of your archangles with a rylia's. this will reduce your mana by 400, and your ap by 149.08, but will increase your hp by 500, and will have the fun (ungodly) added effect of applying an additional 15% slow on top of the 30/40/50% slow, making everyone hate you for making them move at an unreasonable speed.