Since Karma is getting some attention...
Let's talk, about who she was, who she is, and where she can go.
For old Karma, her defining features were: -AoE heal which affected herself, allies, and minions -Enormous shield with enormous damage -Strong poke -Ability to bait people into fights and thrive at low health -Reliance on allies for full potential with Spirit Bond -Complete reliance on obtaining max CDR -Unhealthy reliance on "Shield Bombing" to provide damage -"Mage berserker" passive possibly too strong
Old Karma was confused with her role in the League. She wanted to be a burst mage, and she wanted to be a sustain support. She was very farm reliant, yet was not typically wanted mid because of her inability to full->zero somebody. As a support she was gold starved; support items like we have now did not exist, only items in the form of GP5 which didn't build into anything Karma typically wanted. She offered strong pushing power with her AoE (and minion compatible) sustain, and was relatively safe sitting behind a large shield. Unfortunately, her most reliable damage output abused the high AP attached to her mantra'd shield. Its ability to be cast on minions extended her poke range quite far, the only counterplay being to stay away from your own minions. Her Spirit Bond was a mixed deal; people either knew to run it over things, or had no clue what it was for. In lane it was next to impossible to utilize effectively, except as a slow and speed boost. Her passive led to her becoming quite a bit stronger when she was in danger. Her damage, heals, and shields went through the roof when she started getting low.
The defining features of new Karma are: -Strong poke -Low cooldown speed boost -Renewal offers strong sustain -Situational CC -Unhealthy reliance on R->Q for damage -Somewhat reliant on CDR -Passive offers the same thing other champions get built-in with abilities -Full combo fails to min-max
- R->E replicated by items easily
New Karma's role is also on shaky foundation. She wants to be a burst mage, and she wants to support allies with shielding and movement speed. W->R->Q is undermined by the fact that so much of R->Q's damage is frontloaded, that the aftershock isn't typically worth staying in her W's fairly restrictive range. R->Q is preferred use of Mantra in most situations. R->W can swing a small skirmish in Karma's favor very quickly, but provides no team utility that isn't on W alone. R->E does provide good utility, but requires your team to be somewhat tightly grouped, which is unfavorable with the amount of AoE CC initiators currently popular in the meta. In addition, its full effect (minus the damage portion) can be replicated with Talisman of Ascension+Locket of the Iron Solari. Karma's passive is undoubtedly strong, as Mantra really makes her skills shine, but many champions get this reduced cooldown effect built into their abilities, not a large part of their kit dedicated to it.
In the future, I'd like to see Karma refocused into a mage capable of some form of healing again. It was fairly defining to be able to hurt enemies and heal your team at the same time, and it's very unfortunate she now only thinks of herself with this heal. Some of her R->Q damage needs to be shifted around, less on the initial burst, more on the aftershock. The "meaningful" play and counterplay with it is enemies either being stuck in it, our getting out, and it should actually be meaningful to get out of it. Her other Mantras should provide effects that can compete more with R->Q. Her shield's overall (shield+damage) scaling could see some improvement. R->W may be the door to provide an AoE regeneration effect of some sort, successfully landing the snare of an R->W could apply the initial heal to Karma and nearby allies. This approach makes all three mantras feel like they're making a meaningful impact on the tide of a fight.
Most of all, I'd like to see her passive replaced. Karma deserves a real passive, something to bind her kit together. Something to give her back that feeling of "Don't touch me or you're in for trouble," instead of the current Quantity>Quality feel. As of now it's a rush to dump your mantra into a fight, and try to get a second one up before the fight ends if you can. If she really just can't have two mantras, at least make her one, meaningful.
Tl;dr: Make her mantras (R->W & R->E especially) have more of an impact, or revert to two charges. Let R->W target+heal allies. Shift R->Q damage, less initially, more on the aftershock. Give her R->E better damage, possibly better shielding as well. Give her a real passive, not something other champions get mixed with normal abilities.
**Please, keep in mind this is opinionated, if you disagree, please let me know why in a constructive manner. I am in no way suggesting new Karma is bad, or that old Karma was better, only that more could be done to give her back some of her old feel without taking away too much of the new style. **