I know Ekko is fine right now...but this is a really good idea for his passive...
Lets face it, Ekko kit is diverse and really cool, but it did not really match what was demonstrated in his promotion video. So I thought of something that would be closer to his theme as a time mage/fighter....
What if the passive sent his target back 1 second in time, while resetting his E after 3 ticks? His passive would no longer do damage unless it was triggered by his ult or 3 seconds after ulting. That way he can still keep his ult/passive burst while still fitting the theme of gaining the advantage of going back in time..
The idea behind this matches what goes on in the video. Ekko keeps resting time for his target while gaining skirmish like attacks that counter their next move based on seeing the future. He would no longer gain the move speed buff as his kit is overloaded anyway..
You have to admit, that would be freaking cool to see in the game...