"If you're low, don't chase him". No. If you don't have 3k health and over 100 MR while he has no void staff, don't chase him.
His kit is so damn easy to combo without even using his W. If you have to chase Ekko at all, your carries have to make sure there's at least two or three beef cakes between themself and Ekko because if he tosses his Q behind him while you guys are chasing him, he can then press R, get a second proc of his passive, have done 1.5x his AP and huge bases, then AA with a Lichbane, which would've also proc'd his passive, doing 2.7x his AP. Even without a Lichbane, he can do 2.2x his AP without even landing the 2nd part of his Q. If just the first .2x AP ratio part of it hits to slow the carry and his ghost is within about a 500ish radius, he'll pretty much go Annie on some one's ass and do her entire combo and all he has to do is land the first part of the Q on anyone who's chasing him. Any carry that even gets tapped by the first bit is dead. Instantly.
When we compare this combo to LEBLANC'S own combo... Well.. I'll start with Ekko's numbers with just this tiny combo that only utilizes one and a half abilities and a single AA.
Q's first damage. 160+.2x AP. We'll say he has 500 AP. That's 260 base. Then there's his R which does 500+1.3x AP, which is 1150 base. His Passive then gives him 15+(12xLevel) plus .7x AP, which at level 18 to make it easy is 231+350, 581. Add it all together, that's 1991. That's with 500 AP at level 18, which is a decent amount. Not too many items in.
Now, let's look at LB. Q does 310 plus .8x AP in total, which is 710 damage. R is 600 plus 1.2x AP, which is 1200, then her W which is 245 plus .6x AP, totaling 545. That combo would do 2455.
She does 500 damage, but has to use 3 abilities and has to be within the range. Ekko on the other hand is a little scarier where he does. It's a bit scary.
Now, I know most of you prolly are thinking 'LB does 500 more, that's a lot!', well... You can always E before pressing R on Ekko to help add in that as well, which does 170 base plus .2x AP, so an extra 270.
This champion is meant to be an in and out champion who zones his enemies, which is true because of how ungodly quickly he can destroy a carry. His ghost and his W pretty much describe pure death and are one of the scariest things in the world, but his kit is a little overloaded. Unlike LB, he has sustained damage on his W to execute. It does do 5% base with about 2%ish per 100 AP of Missing Health on anyone who's got 30% or less health. His kit is overtuned, it really is. It needs some nerfs, but not as extreme as some are saying. Like his W could lose a little bit of the ratio and be closer to 1.5% per 100 AP instead and a 1.2x or 1.1x ratio on his ulti, which could be compensated for slightly by making his Q do .3 on the first hit and .5 on the second rather than .2 and then .6 respectively.