This build gets Karma a decent amount of AP and CD-Reduction while keeping her defense up. I had most success with her solo top, but she�s also good duo-lane thanks to her w.

You will usually get some kills early with your q+w, and lategame her team support is insane.

Innate � Inner Flame
Karma gains up to 30 / 50 / 70 / 90 / 110 / 130 increased ability power corresponding to her percentage of missing health.

Heavenly Wave
Karma sends forth a wave of hidden blades from her fans, dealing magic damage to units in a cone in front of her.
Mantra Bonus: In addition to dealing damage to enemies, Heavenly Wave will also heal herself and allies in the cone by 5% (+0.02% per ability power) of the amount of life Karma or her allies are missing.
Cooldown: 6 seconds
Cost: 70 / 75 / 80 / 85 / 90 / 95 Mana
Magic Damage: 70 / 110 / 150 / 190 / 230 / 270 (+0.6 per ability power)
Base Heal: 30 / 45 / 60 / 75 / 90 / 105

This is your basic cone-damage spell. The range long enough to hit 3+ enemies in a teamfight. This is also the spell you will mostly use with your r for your awesome heal.

Spirit Bond
Karma bonds an ally or enemy creating a beam between them for up to 5 seconds. Bonded allies have increased movement speed and bonded enemies have reduced movement speed. Enemy units that come in contact with the beam take magic damage (only once), and champions who pass through the beam receive the same movement speed modifier as bonded champions.
Mantra Bonus: Karma strengthens the bond to double the effect of the movement speed modifier.
Cost: 65 / 75 / 85 / 95 / 105 / 115 Mana
Cooldown: 20 / 18 / 16 / 14 / 12 / 10 seconds
Magic Damage: 80 / 125 / 170 / 215 / 250 / 295 (+0.7 per ability power)
Movement Speed Modifier: 10 / 12 / 14 / 16 / 18 / 20 %

Great slow. Early you use it for escaping, hunting and supporting your ganker, in teamfights you use it on the enemies� ranged carry and hit nearly everyone.

Soul Shield
Karma summons a protective shield on an ally or herself that absorbs incoming damage.
Mantra Bonus: In addition to the shield, energy bursts out from the shield, dealing the same amount of damage as it shields to enemy units around the recipient.
Cooldown: 10 seconds.
Cost: 70 / 80 / 90 / 100 / 110 / 120 Mana
Magic Damage & Damage Shielded: 70 / 110 / 150 / 190 / 230 / 270 (+0.8 per ability power)

Great shield on low CD. The damage is worth a Mantra, but has a tiny range. Make sure to coordinate with your team�s other shields.

Mantra
Karma empowers her next ability to do an additional effect. Karma gains a charge every 30 seconds and stores up to two charges. The refresh rate is reduced by Cooldown Reduction and does not progress when having max charges.

I don�t know since when tiny purple fans circling around you are called mantras, but you have got them. With 18s minimum CD and all your other skills on much shorter CDs, don�t waste them before the next teamfight.

+ Effective at solo top, 1v2 or duo lane
+ Decent AE-damage at long (w) and medium (q) range
+ Great percentage-based AE-heal on low cd
+ Can protect carry (e)
+ Great farm late
+ Okay last-hit animation

- Prone to burst
- No reliable single-target damage
- Mana dependant early
- Requires tight team positioning
- Has to fight near enemies in teamfights

Pretty basic caster runes.

Red: MPen
Yellow: MP5/lvl. Still needed after nerf.
Blue: CD/lvl. May use flat CD or AP/lvl.
Quin: Flat HP. Please use them.

Basic caster masteries. Adjust them if you use different summoner spells. If you want to adjust, make sure to get CD-Reduction, Mana and MS (she requires lots of positioning).

Great:
Flash � always good
Teleport � must have to outlane solo opponent
Exhaust � if rare on team

Okay:
Ghost � but you have your w
Clarity � if your team also needs it
Cleanse � depends on opponents
Ignite � okay, not recommended but some love it. Free 10 AP
Clairvoyance � someone has to get it. You can
Fortify � someone has to get it

Don�t:
Rally, Revive, Smite

On start, grab a crystal and pots. Build Tear asap, you fill it slowly.
Boots are Ionian (assuming you wont get blue buff) or Mercs.
Full Archangel is expensive, grab some AP and build Spirit Visage.
Build Archangel and your core is complete.

If you get Zhonya�s, use the active.
If you get Lichbane, use the passive.
If you get Banshee�s know when your shield is down.

Other possibilities:
RoA � just a bulk item. Get it if you get bursed down too often
Rabadon�s � if you don�t need defense�
Deathfire � great burst, but wasted if you get over the CD-Reduction-Cap
Abyssal � even more MR and support your fellow mages
Mejaijs � you get assists for heals

Your q is lanestaying-power, harrass and farm in one skill. Max it first. Get one point in each ability by 4, two in e by 6 (against your opponent�s ult). Then get three points in w, that should be enough to catch anyone. Max e, then w.

Please comment on my (first) build :)