As zed, The first item procurement will make Zed a deadly champion to deal with. He should be looking to roam to other lanes and clean up kills on low-health/overstaying enemies.

Level 3 is a decent power spike as Zed will now have access to his overall burst combo. He can quickly go for short burst trades and proc his runes with these abilities. He can spam them quite fast as well since he is not dependent on mana.

Level 6 is a significant power spike for Zed. This is where he unlocks his full potential and can make the plays and the moves to make enemies wonder what that was. He should also be able to dive low health enemies and escape unscathed. As zed, The first item purchase will make Zed a mortal champion to manage. It should seek to wander other ways and clean kills on low-health / surstaying enemies. Level 3 is a decent power peak because Zed will now have access to its global burst combo. It can quickly go for short exchanges and runes with these abilities. It can spam them quite quickly as well as it is not dependent on the mana. Level 6 is a significant power peak for Zed. That's where it unlocks its full potential and can make games and movements to make enemies wonder what it was. It should also be able to dive low-health enemies and escape unharmed.