So I bought her since she was released, and it's pretty obvious, there's NO way she can keep up with Sona or Janna. In addition, she's so poorly designed that her unique nature doesn't really matter. Here's the rundown why she's a terrible hero.

-1) Terrible passive.
The ability to gain more AP the less health you have COULD be a nice idea, just not on her.
First of all, Karma should NEVER hang around with low health, one focus and she's done for. Since people make it a point to target the support first, so even if you DO get lucky and manage to escape with low health, it's suicide to stick around with your "uber ap". Since her heal is short ranged, she has to get back into the fight to contribute some heals. Not to mention, it gives the enemy team even more reason to focus you down. Overall, terrible idea for a support to have.
Also, hilariously, try playing karma versus Veigar's ult. "Oh so you get more ap the less health you have.... PRIMORDIAL BURST..... dead from half health...

-2) Her "Heal" is terrible.
First you need to use a Mantra charge just to use it. That in itself makes it inferior to other champion's heals. Then it's the fact that it's "attached" to her Heavenly Wave. Now, on paper, having a spell that both damages enemies AND heals allies would be overpowered, but it'll mostly result in unwanted pushing of lanes, accidental minion aggro, and killsteals. In high ELO stealing kills from your carry because you were only trying to heal will piss people off.
Lastly, extra AP does NOT increase the fixed heal amount, only the percentage one. Ignoring the fact that you need 250 AP JUST for another 5% bonus heal. (so you heal for 10% of an opponent's missing health, soo on a guy who's missing 1000 hp you heal for 100, wow...).

-3) Her Spirit Bond is unwieldy, and criminally weak at lower ranks.
This spell was terribly designed... End of story. In order to actually get to use it's AOE slow and damage it requires that you pass the beam through the target. So, either you need to make the guy you just leashed run around the field (negating the movement speed buff to begin with), or that you step OUT of position, in order to try to maneuver around your enemies, exposing yourself to a gank. Although the 300 damage does sound nice in theory, it requires too much busy work to get the most out of it. Also, the mantra effect is pathetic, since you're at most getting a 40% slow, which even orianna has on her spells.....

-4) Her rank 6 spells are pathetic.
One of her supposed strong points is , that since she's lacking a proper ult, her normals abilities have 6 ranks instead of 5. But instead of being stronger than other characters' skills, it simply means that their effects are spread out more, requiring MORE levels to get to the point where you'd be as strong as comparable characters.


-5)Her builds.

People keep telling me that Karma isn't a true support, but rather a mage with support characteristics. If that really is true, there really ISN'T any reason to play her.
So, let's look at "mage" karma.
Her full combo is Heavenly Wave, Followed by a mantra shield, then Spiritbonding SOMETHING other than her target so that the beam passes through them.
Well, you need a mantra charge to use the shield's damage, and since the shield has a 600 AOE, you won't always be able to target yourself with the shield, and you won't always be able to use it. And you need to cast your Spirit Bond in such a way that the beam passes through the target. IF there aren't any creeps nearby, good luck....
But worse than that it's her items. Karma requires AP to keep up with other enemy mages, so she needs to farm , thusly minimizing her role as a support EVEN MORE.
Yes, her shields and heals will be better, but early on it;ll mean less money spent on wards, less money for your carries, and any accidental killsteals from the damage her heal and shield do. So, why not just get a mage?

Lastly, think about it this way: Do all the additional effects her mantra charges get REALLY offset the bonuses from something like Sona's AOE supress, Soraka's Global heal, or Janna's knockback?

Conclusion. She's weak and poorly designed. You want a hybrid healer? Play Taric or Nidalee instead.

She is a champion that requires farm to be strong, while having no hard cc. This is a setup for fail. Either they need to be good without farm (Janna and Sona) or they need to be super strong early/mid game while having a role late game (Nidalee and Soraka.)

Erm... I have recently picked up Karma and started using her almost exclusively, and while she doesn't build like a true support (tanky cdr) she also doesn't build like a pure mage either (deathcap, AAstaff)

the build I'm using is from something I saw on mobafire, and the way I play her is as bait, because she does it very well early game.

take flash/heal, build typical mage masteries and runes (the build i saw on moba said to use pure AP instead of pen, pen doesn't affect heals or shields so it makes sense)

start with Q, then get E, then QWE and level Q and E evenly.

lane with a tanky dps or dps guy like xin or yi. just try to last hit, if they start harassing you guys, b a little bit, and start mantra shield bombing. Mantra + Shield on the farthest minion from you (closest to them) and you will make them fear you. Once you get the hang of Karma you can bait people like you can't imagine. Let yourself get around 25%, and let them initiate, run into a bush so they have to get really close, then wait for them. Mantra heal, mantra shield, heal. If you have a smart ally, you probably just got a double kill.

I have used the above strategy in about 90% of the games I've used Karma in, which isn't many as I said I just picked her up, and almost every time I have gotten at least one kill and haven't died from baiting.

Her build is start dorans, rush ROA, then glacial shroud, abyssal, deathcap, banshees/frozenheart. (whichever you need more at the moment, get the other one after). It works pretty good, makes her deceptively tanky for a support but burst like hell still. Her heal is actually pretty powerful, it's what makes her baiting utility ridiculous. Let them get low, then burst heal with mantra heal + summoner heal, and a mantra shield ftw.

Karma's passive is honestly a huge burst for her considering with her shield/heal combo she is very misleading and unless you have a LOT of burst or heavy CC so she can't cast she will most likely turn a battle/gank around.

Also her heal is only small if you use it 1) when an ally is near full 2) without a lot of AP. I fought a Karma once who had enough AP to be healing for 17-18% (passive depending) of allies MISSING health + whatever the flat amount is at max rank. Imagine bursting down a team only to have them jump back to half from one spell?

Her Bond could use some work, but honestly that's her get away/help an ally run, imo.

Also its really not smart to compare supports considering they each do a different thing. Sona is a buffer with spam heals and a AoE STUN (not Surpress), Soraka is a powerhouse healer that can either stay in the back and heal on CD (and give mana back) or hop in and out and lower MR and silence. Janna is all about controlling her lane through her CC (knock up, slow, knockback) while also protecting her tower/allys (shield). Karma's role is to mislead people with her power. Her shield scales as well as Morgana's, and does a huge burst of aoe damage with mantra. Her heal can heal as many people as can fit, for up to (as far as I've seen) almost 20% of missing health, and she can slow/speed up anyone trying to run.

Could she use better flat scaling per level- probably. Does it she NEED it? No not really, not if you're good with her. But she is FAR from terrible.

to quote my posting about a karma buff:

so we all agree she needs a buff? GOOOOOODDDDDDD!

i hear that on EU servers they tend to like using karma as a support, and since EU > US, i tried her out.

She doesn't disappoint, she actually does decent amounts of damage and is able to keep her support role. I don't understand what you're talking about when you say she's bad, and if she gets a buff? Even better (for me). I do realize her spirit bond slow is lacking, but the slow is just kinda there, i don't really ponder it's effects in whether it's a good or bad slow / speed up. I just use it. Like if a rammus is powerballing, SPEED UP! If i'm being chased by two people? Put the bond on the furthest champion (that's in range), tag him, then everyone else in between will get slowed (most people don't really understand that there's a slow involved).

If your team is kinda leaning on the AP side, rush a will of ancients, therefore you help out EVERYBODY with spell vamp and magic. If they aren't, get a revolver at the least (more heals) and then get a rylais (more slows).

Plus she's a GREAT lane addition (heal, damage, slow, shield), not to mention a great solo (Shield blast minions on a minion then Wave).

TL;DR Don't know what you people are talking about.

So buff her.