If Riot wants to only slightly nerf Zed, why not start with removing unnessasary power?
Upon arrival, he applies a Death Mark to them and ghosts for 3 seconds
Is ignoring unit collision even necessary? It puts him on top of his target, and he blinks back to his shadow after he's done. Nobody would notice it being removed, which is fair enough reason to remove it. Its not needed.
Passive: Zed's bonus attack damage is increased.
What is the purpose of this? He already has his innate passive, which is the main reason he'd auto attack. Its removal could be compensated by increasing ratios by the relevant amount. His auto attacks (the only thing this affects that could not be compensated for via ratios) do not need to be made intrinsically stronger because he already has his passive.
Active: Zed spins his blades, dealing physical damage to nearby enemies and reducing Living Shadow's cooldown by 2 seconds for every enemy champion hit.
Is the CDR on Living Shadow really necessary? What does it accomplish for his core gameplay, outside of adding to his already significant safety?
Living Shadow: Active shadows also slash, dealing physical damage to nearby enemies and Slow icon slowing them for 1.5 seconds. Mimicked slashes that hit targets affected by the primary slash enhance the (base 40%) Slow slow by 50% and restore energy, but deal no additional damage.
Does Zed really need a 90% slow? This could be reduced to 60% total (30% base+30% from mimicked ability), which would allow Zed to accomplish the same things just as easily, but without being as oppressive in many circumstances.
I'm not saying he needs all of these things removed to be balanced, I'm just asking if they're all really necessary, especially the ghost on his ultimate that's almost never needed.