Ekko's Chronobreak seems confused
R: Chronobreak No Cost 90/80/70 sec Cooldown Makes Ekko invulnerable and untargetable, and teleports him back to wherever he was 4 seconds ago. Ekko heals himself for 100/150/200 + 20/25/30% (+0.06 AP?) of the damage taken over the last 4 seconds, and deals 200/350/500 (+1.3 AP) magic damage to all nearby enemies on arrival.
It's a escape tool that wants to help you reengage but demands that you don't actually use it as an escape if you want to get your full damage burst off. That identity issue combined with the prediction necessary to use this ability to its full effect just makes it seem weird - You have to not only predict where your enemy will be in 4 seconds but you have to actually have been in that place 4 seconds ago and be willing to go to that location without an effective escape tool still available to you.
It seems like this ability is trying to be very different things at the same time in a very confused way. I feel like it would be better as a personal escape + steroid(Movement speed and attack speed?) rather than escape + bomb. Maybe give it some charges to sell the feeling that you're actually retrying failed attempts at something and improving every time
being a prime example.