Originally Posted by Samizul
This is exactly right. With his early game poke and his passive he was too dangerous from 6-9, especially around level 9 when his Q is doing a lot of work. It's very dangerous to be near a Zed with his ult and ignite up if you're below 50% hp, and he's pretty good at getting an enemy champ down that low in lane.
We also wanted the "pop" from the ult to feel good - sometimes it could pop for like 20 damage - so now you'll always see some damage from what is arguably the most exciting part of his ult.
This is exactly why I felt that the change to Zed's ult was perfectly fine down to 20%. Mark of Death and his passive make it very important to time and wait until an enemy is 50% or less. It also makes successfully killing an enemy champ with his ult early game really satisfying because it's not an insta-kill.
Also, one thing to consider when using Zed's ult, is that you DON'T have to target your mark initially with all the damage. I've gotten plenty of double kills by Marking an Enemy and using the shadow to kill a nearby champion, while AAing the marked champ. Granted since your next to the marked champion, they'll be taking extra anyway, and throwing Ignite and an Active from Hextech Gunblade (or as I normally play 3s Blade of the Ruined King) for added measure.
Loving this champ Riot! Keep up the good work and I cannot wait for him to be released to the main servers!