I just want to take a moment to point out that Zed does purely physical damage, none of his abilities do magic damage.
In fact rushing a Zhonya's Hourglass is one of the best ways to counter him as an AP Champion, the early seekers gives you plenty of armor against his lvl 6 all in and by the time he gets really scary (lvl 11+) you will have the active to completely negate his Ultimate. Although counter-intuitively if you are an AD you will want a QSS, as even though it is a pure MR item it will cleanse his Ultimate before it procs allowing you to survive in a teamfight against Zed as the roughly half of his burst comes from the Ultimate proc.
Anyway nvm me, I'll go back to lurking. Just couldn't let that one sit there for newer players