Zed's ability to kill people isn't the issue
Zed is one of the more healthy assassins in the game when it comes to the way he actually all-ins you. The problem is the fact that he's got a strong all-in on top of a really powerful laning phase. Especially after the last buffs, his harass is reliable and does a lot of damage while having no long-term cost. Ideally, the right way to change him is to reduce his ability to just harass people down while keeping his all-in damage the same.
As such, I think a good solution would be to reduce the damage on his Q and then increase the damage he gets for hitting multiple Qs on the same target to compensate. He does sometimes get multi Q hits in lane, but that requires him to take a few more risks and is easier to deal with, and his really fast WEQ combo wouldn't be as good of a tool for poking people down in lane.
His all-in would do about the same damage if he was landing multiple Qs, so all this does is make him need to take more risks to kill someone. Strong manaless harass is rarely a fun thing to deal with (
have all been problems in the past because of it), and I think this is the best way of reducing Zed's harass without weakening his ability to burst people down.
"Oh, hello. Vere did yo health bar go? Oopz."
: Mobile af, even more than Zed, and such sustain after level 6.
: Insane ultimate, three slows in one kit, versatility, pretty good laning (mana-dependent though), a stun (kinda hard to land)
: Troll pole, insane burst, easy to land ultimate with enormous damage, versatile, pretty slippery (less so than Zed though)
: Absolutely ridiculous AoE damage and burst
: He's really rather meh right now, but good burst if isolated
: Ridiculous damage with good sustain if you build him correctly, very simple, hybrid damage, gotta go fast, can kill many people at once
: Pretty mobile, fairly long range, versatile, tons of burst
: I don't even think of him as an assassin anymore tbh
: Insane one-shot capability with no counterplay (but that's about all he brings to the table)
: Mobile, mind games, high early game damage and insane ganks/steals
: Ridiculous burst with very little counterplay. I know most say to buy a pink, but seeing him doesn't help when you're already dead. He's mobile, fairly slippery, and can kill many people at once.