focus on upgrading your E and only 1 point into Q, if you're against talon you should ignore upgrading W as that will be near useless, save your q for when he does that teleport thang, stay inside your minion waves and you should be able to outtrade him.
If you're in mid, you shouldn't be placing your mushrooms offensively, but more defensively. Keep some in your tower area and use the rest as warding bushes. If you're top, place the mushrooms in both the bushes and the corners, but make sure not within the general area of where the minions will clump up. place one or two at your tower.
Zhonya's.
Initially, his waveclear ability will outtrade you because of its range, due to delayed cast and speed. try to bait him into using it, or at least get 2 darts off if he hits you with it. When he is oom, harass him even more. don't use your blind unless he teleports to you.