Change Ekkos R Heal into a Shield instead
I'm loving Ekko as a champ, this is the first new champ in ages that I want to main, but he's too safe. The ultimate of his shouldn't heal him, just like in the trailer he should feel the pain of his mistakes. As it is now, if he gets in over his head he can do just undo everything that happen.
Overall I don't find him Overpowered but it ticks off many players that you essentially have an undo button every 100 secs. That way if you ignited him you still a chance.
The shield shouldn't last too long, and it shouldn't go over his max health. That way he can't pop up in the middle of the group with his max health plus a shield on top of the W Shield.
I'm not very good at explaining myself but hopefully I wrote it well enough for you to understand.
TLDR
He should still pay for his mistakes, if he jumps into a group of people and ult away he shouldn't be able to undo the damage. He should still risk being in danger of lingering effects as bleed/ignite/ or delayed minion/champion attacks