About Karma (Why I think You're Looking at this Change the WRONG WAY)
So, I've been playing Karma since the day she was released. When she was garbage, when she wasn't (I never really thought she was garbage), right after the rework, through all the changes.
People seem to have a fundamental problem with how Karma's kit works, and it's being manifested with a lot of people complaining about E shield losing damage. Let's look at how Karma's laning phase plays out and your options.
Now, people talk about Karma like she's a poke heavy mid laner. There's a fundamental problem with this that I'd like to look at - primarily the fact that, at least in the mid lane, your opponent is generally going to be behind the creepwave. This means that in scenarios where you are zoning your opponent, she can poke very well (by standing beside the creep wave to pressure opponents back, they have no creeps to hide behind). But... How do you reliably create this situation?
Looking at Karma's kit again (and this is how I play her now) - Karma is an all-in/trading mid laner. My play pattern looks like this - enemy opponent either uses spells on the wave or comes forward to last hit (depends on laner - if they're skillshot heavy I like to abuse E). Karma E's herself, comes forward, W, kite kite kite, Mantra Q. This will do 30%~50%+ damage to most midlaners, even at level 3, thanks to Mantra'd Q's absurd early damage.
If you want to kill someone with Karma, it is very rarely (in the laning phase) accomplished by poking them down with naked Q's. The Q range is not really THAT long, the explosion is big but the actual projectile is also big (making it very hard to shoot through creepwaves). It is almost always accomplished by using your W to root someone.
Looking at the changes, this means mid lane Karma has MORE options available to her. "But Cat, she can't get all her health back with one spell like before!"
You're right! But she still generates health swing and (honestly) having a health swing that isn't based on Karma's %HP is a pretty big buff to her lategame ability to swing trades/fights. You're going to probably (I would say definitely if you make spellvamp) outheal the old heal, but additionally, the target takes 10% additional damage.
This is a HUGE swing to Karma's ability to make picks and catch people out of position (which she already excels at) - giving the team's damage a slight boost.
And then we get to the E change.
I have seen multiple people saying things like "BUT MANTRA E DAMAGE WAS SUCH A GOOD WAY TO CLEAR WAVES!"
If you're clearing waves with Mantra E and it isn't pre-rework Karma, you've just wasted your Mantra. Looking at the damage it's clear - Mantra Q is superior for damage and waveclear in every scenario. You can hit the entire creepwave with it, it does more damage, slows, and you can use it from further away.
The shield is better (again, buffing her teamfight/skirmish presence) when Mantra is used, and with more Mantra available to her due to scaling CD/CD reduction, Mantra E is more available to her. All of these things are huge buffs.
So people talking about mid lane Karma being gutted? I've played mid-lane Karma since rework (since before rework) and, post-rework, have not felt Mantra E important to waveclear. Additionally, aside from a few fringe cases, the heal on W is also not integral to her performance. It's unlikely that this change will "gut" mid-lane Karma (anymore than she's already gutted for just working so well with another person).
and you'll be seeing that Mantra W up a lot more often.