I'm a Zed main and I'd like to share my thoughts
Before you start down-voting me to oblivion let me please have a conversation with you. I actually AGREE that Zed is in a bad spot right now and does need some changes. But I would like to share my thoughts on Zed.
A quick preface I have been a Zed player since mid season 3. He quickly became my favorite champion, and I played him through ALL metas. When he was strong or weak or OP, or whatever. Changing Zed will not change my desire to play him, and playing him through all the changes in the game since mid season 3 has given me a pretty objective perspective on him and his strengths/weaknesses.
Can Zed's kit be balanced? A lot of people have short memories. Early to mid season 4, this game was considerably different. At that time, Lulu, Soraka and Ori were the dominant mid laners and the meta called for support style mids to support the strong bruiser/carry style junglers and and AD carries. At this time, Zed was not considered OP, in fact, anytime someone would complain about Zed on the forums they were usually down-voted into obscurity. Alas, the meta has changed -- assassins are on the rise again, and Zed has taken the forefront.
I have read a ton of threads in the past month that have said that "Zed can simply not be balanced... His kit is just way to strong." And I think that it only takes looking back 3 short months to see a time when he was considered a bad pick in both competitive play and solo-que. So a massive overhaul is not what Zed needs, he doesn't need a rework and he doesn't need a changed ultimate. His balancing issue is strictly a numbers problem.
Why so OP all of a sudden His buffs this summer were not the reason for him being considered OP right now. The meta has just happened to shift back to him being in a dominant position. I mean, think about it, the mids rising to popularity right now are all similar to Zed (assassins with good lanning-phases and roam potential). This is due mostly to the changes in the jungle, discouraging, or at least evening out, early game pressure.
Once Zed is nerfed, which is probably inevitable at this point, he will no longer be over-shadowing the major problems with EVERY assassin, not just Zed. And pretty much every popular assassin right now has the same issues. So if we are going to put Zed under a microscope and talk about his strengths, we should probably do the same with other assassins that have similar kits.
The other strong assassins
I think that if we are going to talk about Zed not having the "risk vs reward" play style that assassins are suppose to have, then Fizz should be right there next to him. Every problem concerning Zed right now can be applied to Fizz with the exception of being manaless.
With the changes to her W, she is once again strong, and will surely make a come back. Plenty of wave clear, and a very safe playstyle with considerable burst.
She was just recently nerfed, but still the same issues. Including being manaless.
Not the same wave clear as the champs above but enough damage to easily put Zed to shame while having a crazy safe play style and no mana.
Ahri is in a weird spot, really strong but very under-played. I expect she will make an excellent come back. But maybe not necessary on this list.
All these champs have glaring issues with the meta right now, and any one of them could be in Zed's spot easily. I think as a community we need to examine the role in general, not just Zed.
What Zed needs I think Zed is in need of some nerfs, and here are my thoughts. First, death mark cooldown at levels 1 and 2, should be higher. It is up to often in the lanning phase for mages to have opportunities for counter play. Next, his W should have a significantly longer cooldown, but the cooldown reduction from his E should be applied only on Zed's E not his shadow, and be much higher. This means that Zed still has sticking potential, but not as much safety, poke in lane without taking risks. Finally his Q damage should be slightly reduced at early levels.
tl;dr Zed needs changes, but every assassin does, let's not go crazy here with all the Zed hate, he CAN be balanced.
's case where ulting into fight is a guaranteed reset. What do you do when you see 
' as serious reset dependent then he's probably the most balanced reset-wise )
gets kills by default.
combo. These two items give Zed raw chasing and dueling power, while not forcing him to build raw AD items like
. Right now, Zed is an assassin who can prioritize things other than AD and still burst, due to his high base damages. To this end, Zed's base damage should be toned down a notch, while his AD scaling should be increased to compensate. While not a flat nerf, it actually adds counterplay to Zed's kit (at least, I think so). As a Zed player, what do you think about this?