Karma is seriously a toxic champion.
She can chain slow you AND speed herself up, while shielding herself.
She does more damage the lower life she is.
The defensive and offensive power she provides is not balanced.
I'm thinking that YOU'RE thinking of the Karma from 14 months ago.
Can't be hanging out at the bar with 
. Never ends well.
You're thinking old Karma when it comes to lower hp = more damage as a heads up. She doesn't so that anymore.
Overall, Karma has more utility than Soraka, more burst damage and more complete versatility. But she is much more of a reactive champion than sor. One of Sor's main probelms is her high out of combat sustain, meaning she can just back off for a second, heal herself for a lot and keep on trucking, combined with the fact that she has a free damage spell as well as decent sustained damage with Starcall.
Karma doesn't have out of combat sustain, she doesn't have good sustained damage until she addresses her mana costs and her ult is easily exploitable (an ulted Q means no ultd W for example). She's strong, don't get me wrong, but there's a lot more you can do against her with proper knowledge and play than you can against a patient Soraka.
She can chain slow you AND speed herself up, while shielding herself.
Yes, but that's reliant on her hitting every one of her q's.
She does more damage the lower life she is.
As others have said, this isn't true any more. It used to be true, and was toxic, hence the rework.
The defensive and offensive power she provides is not balanced.
I think what you're saying is she has too much offensive AND defensive power. I'll disagree here; her only offensive power is really "run at them and try to get off a root," which isn't exactly reliable. Furthermore, Karma's damage falls off after 4 or sometimes 5 items (kind of like renekton).
As others have noted, Karma really only excels if every ability hits, i.e. no broken chain, all qs (with their small hitbox) connect... then there is the fact that any champ with closers or hard cc plus burst can pretty effectively destroy karam before karma's long-play style can be effective. (Why most professional teams with karma loose their games, due to how instantly game changing moments happen late game, there isn't time for her to have enough impact.)
For Karma she has to be spot on every time over time to have the same effect as another champion being spot one for one great quick play.
