State of Ekko
I think Ekko is a very interesting champion design wise and appears to be a lot of fun. I think you guys did a great job creating an engaging and interesting champion. I do have a few qualms with Ekko's current balance, however. Certainly a highly mobile, massive burst, assassin (as most are) doesn't need to have that much crowd control, shielding, and burst heals. I honestly feel like this champion has no weaknesses (he is squishy but it doesn't really matter when his shield and ability to heal combined with massive mobility negates the weakness) and is basically what would happen if Le blanc had self healing, shielding and aoe cc. I'm not sure what you decide needs to be done in order to balance him, but it is most evident that he needs adjustments. He outclasses every other assassin in the game. This champion, for me at least, is a permaban for his sheer potential to wombo and execute an entire team by himself. I look forward to seeing what becomes of this new champion and hope that, once thoroughly tweaked, he can offer a fun experience for both people playing as Ekko, and against him.
and
add more to his burst. So let's say Ekko just has these two items and no runes or masteries. He gets 600 (ability ratios) + 100 + 80(75%AD as lichbane base damage) + 120 damage from these two items (Luden's Nerf = .1 ratio) = 900 damage from two items before base damage (about 1180 damage at max level) and resistances. You can't really say that for any other champion. His damage is conditional, but you could say that about any champion really. Because he makes such good use out of Luden's and Lichbane, I think he can afford to have some of his ratio's nerfed.

's current problem is just that he deals too much burst damage. On release, he was touted as an assassin who traded off instant damage for massive utility and crowd control, and while his utility isn't too terrible to deal with on its own (his crowd control and ult are both heavily telegraphed, as is the bulk of his Q and passive damage), he can still deal enough damage in a single QE rotation to burst down most squishies. At this point, I think just toning down his numbers, especially the damage on his Q, would make him a lot less terrifying to deal with, and would finally bring out his intended weakness (he does telegraph his biggest sources of power pretty heavily, though, which is a significant weakness).