Ekko reintroduces the same problem Akali was nerfed for

Patch 5.2: Akali:

We're going to be blunt: Akali is a prime example of an assassin with low counterplay, largely due to her reliability and target selection. While Akali's ability to blow up highly mobile targets is valuable, it also means that once she gets even slightly ahead, she's got all the tools to smash her way to a victory. With these changes, Akali will have to be a little more clever with her use of Twilight Shroud to proc Mark of the Assassin, opening up more difficult matchups against melee champions that she previously dominated. Or, as Akali would say, "As balance dictates."

This was the patch her E stopped triggering her Q mark. Why? It was all basically point-and-click, fast and too fluent. It means it gave her opponent no reaction time and dealt absurd amount of damage almost instantly.

Now, Ekko's E does the same thing. The issue is, as it's second part is an AA, it procs on-hit effects such as Lich Bane and Hextech Revolver. I'd go even further and say it's even worse, because - unlike Akali - the first part can jump over the wall even if he doesn't have vision over his enemy and the second part is a blink, which defeats the purposes of spells many midlaners rely on in situations like this: 's R, 's E, 's E. Additionally, if Akali fails, she needs to try to survive the rest of a teamfight/the response from her enemy in her Shroud, but if something goes wrong with Ekko, he just presses R and is out. Not to mention Akali, to do that, she needed to use her Q, R and E, which at least is an attempt to "combo" spells, but this is all loaded only in Ekko's E.

My suggestion? Make his E so it doesn't proc on-hit and actually treat it the same as Akali - he has to AA once more to proc them. To be fair, he has enough survivability to deal with it in teamfights (his shield + stun and untargetability + heal + way out compared to Akali's heal and stealth).