This is a guide for a friend of mine who asked me how to build Karma. Personally I feel Karma is a tough champion to play partly because she is so flexible. So a simple build list would not suffice. I've played her for a couple of months every now and again but I am no master so criticism is welcome.

Pros:
Fun
Rewarding
Flexible
Survivable if built right

Cons:
Hard to play
need to max cooldown reduction
Beam spell is exceptionally hard to use and feels almost useless at first
Feels like you are lacking a 4th ability.

Aura Support:
Basically you want the aura's you have to be tailor made to benefit your team. You try to heal and speed people in and out of battle as needed, all the while absorbing damage. This is more like a baby sitter.

Tanky:
Very similar to aura support karma, but this one needs to farm more and so eschews the gold/5 items. Not tentirely sure if it's a build all on it's own and I think this one needs a bit of work, but it plays almost just like aura support your items are just a little bit more selfish.

Ap:
Karma is a great mid game AP carry. However she peters out late game. This doesn't really suit your play style either. However if you need an ap carry cause some guys switches to janna after everyone else has locked in... or someone disconnects she can thrive early. Late though not a big fan.

AS said before Cool down reduction is critical, so when you go to build Karma you need to look at buying cool down reduction to fill up your holes. Most commonly you get 9 from talents. Leaving you really with 30% you are going to want to fill up in runes/items. Flat cool down gives you about 6% which means you have 25 left to fill, if you then buy quints you can pretty much fill it with one twenty percent item. However you go make sure you have those items/ runes mapped out in your mind that work with your build

Standard 9/0/21 masteries. You like Clairvoyance too so the build works really well.

This ability is a big part of the reason why as Karma you can eschew some of your ability power items for survivability. it gives you up to 180 AP when you are at level 18 depending on if you are at low health. Now you need to be dead to get that 180 AP so it's not much use but that's more AP base then a death cap, and yes Death Cap's bonus affects it too.

Which asides from just not wanting to die you build survivability. the lower you are the more your shield protects and your heal works. Which is part of the reason guardian angel is imo a good item on her

Mantra charges up your spells.

As you can see the cool down reduces as the game progresses. This is another reason why karma can go tanky if she gets cool down reduction as the game goes without seeing too much depreciation in her dps. That being said it is a whopping 40 second cool down initially. Use it sparingly or when you have 2 charges up. If you get into trouble not having a mantra charge can cost you your life.

Healing and damage all in one. It heals for a percentage of missing health so you get better returns on people at lower life. Which is good cause that's who you want to heal. Mantra adds no extra bonus damage but it heals anyone under the cone. Very good in team fights.

This is a great farming ability and one that some people start leveling first. Theory being why have to use a mantra charge to do damage? Mantra is on a 40 second cool down initially right? I've experimented not a huge fan but it is part of the decision I make when I go to build her every game.

This spell works by choosing a target friend or foe. The target becomes the an anchor for the beam you being the other. The beam is broken when the two anchors are too far apart. The anchors are only affected by the speed modifier. The speed modifier and damage is applied to any targets in the beam's path. A mantra charge only increases the speed bonus.

At first glance the worst spell in Karma's arsenal. Then again at second glance it still probably is. The damage effect is really tricky to use right. However it does have some redeeming qualities. It has a high AP ratio, and it slow's speeds up multiple characters. This isn't an insubstantial amount either 40% when you use your mantra on it. Personally I use it to speed in combat beasts like Mordekaiser who has no gap closer. Or I use it to speed up a wounded mage trying to escape the clutches of death in the middle of a team fight.

It has a fairly low cool down and so it does pretty goo when you look at trying to influence the flow of a fight. Since we built survivable and want to be in the middle and take hits it probably is going to hit people. It helps you get across the map with a a friend quick or escape ganks as well.

This is majour damage lots of range. This is a great harass ability and your main source of damage. It's great to use to harass melee trying to farm minion kills, and to make people think twice about sticking around to gank a target that got shielded. This has good ap ratios as well. The issue with this ability is that to do damage you need to use a mantra charge.

Interestingly enough the power of this ability is one of the biggest obstacles to playing Karma appropriately.

Laning:
Babysit, buy wards, harass from the bushes, try not to die. After you get out of the laning phase you are almost unkillable.

After laning:
You can stay and farm in a lane for a bit if there are no majour team fights. But the worst thing you can do is to wander alone. You aren't beating anyone 1v1.

Team fights:
The hardest part about team fights is you speed in mordekaiser, drop a big aoe shield on your carry throw out a big aoe heal on people and then.. auto attack. You finally got your shield up and oh.. no mantra charge yet whatever need to save ahse, now you have your heal up but you r thinking man if only I'd had had the shield damage up we could have won earlier.

Patience is key on karma. Before you go into a team fight look at your build. Look at your team, and their team. No ask yourself what charged ability is the most important? If I don;t have tons of AP the shield pop isn't as good as the heal. I mean if you hit two mantras use one don't let it sit just ask yourself how do I want/need to play this team fight and try to play it like that. It's the hardest part really. Especially since sometimes it's the best to do heavenly wave/Spirit bond powered up rather then the shield.

As Initiator:
Since we have tons of health and a 40% slow, and the heal works way better at low health, and a guradian angel you are not a bad initiator. If they waste their cool downs and focus you your team can come in and do some damage. If you die you come back and let off a wicked strong shield/aoe heal.

The hardest part for me of the builds. If you go aura make sure you are looking at what your opponents are playing as. Frozen heart, zhonya's hourglass, sunfire cape, randuins omen, can all be great picks against certain team compositions. Justr take a look but make sure you keep Karma survivable so that she can tanke some punishment and get her high AP returns.

Tough but fun. Build her survivable and based on the teams needs and play her with some poise and that's a winning combination.