Hi, This is my Karma guide!
Here i play Karma very offensive, she is great support & deals tons of damage.
Build name: it's what a dude said ingame, funny moment :p.

This is my standard Caster page.
10% magic pen, AP/level & some flat AP to give a bonus early on.

Hoeray the masteries!
Again standard caster masteries With the focus on: Teleport, Flash, Movement speed & Increased duration on neutral buff. This u need very much mid&endgame. Your jungler won't need it anymore and buy heaving the awesome blue buff, u can constantly heal, shield and damage around!

The items. This might be a little bit hard at first, but definitely pays off!
You start with Dorans Ring. i usually hate all the dorans items, but on karma & this build, It's ****ing awesome! The dorans give you enough mana regen untill late mid or late game (with taking the blue buffs) + some health and AP, it's perfect! Then u hold it out until you can buy Needlessly large rod(make sure u got teleport because u dont have any movement speed). You probably will have a kill or an assist before that. IF you do die, and dont have enough moneys, you can buy blasting wand & boots.
Important: the reason why i dont buy boots is that it's kinda useless early game, since u are a caster, u have to stay behind minions, and only overextend when u sure can get kill on the lane. And u always have your spirit bond & flash to escape.
Advantage: When u have your Needlesly += 80 AP!! your spells deal significant amount of damage SO go into your lane, let your partner initiate, mantra + shield him, healing wave (no mantra) and prob gg :D. ALSO: once and a while buy the blue elexir, AP & CDR!!!
Next: build into you Deathcap & Ionian boots. Next buy Giants belt, some more HP(karma's passive) and now follow on the build :)
Next: Room for 2 more items! u can go banshees / abysall / frozen heart, hourglass, u know some more defending items OR if they(4of5 players) are heavy on MR, buy void staff.

upgrade Healing wave & soul shield. 1 in spirit bond @ lvl 4, only use to escape / chase.
upgrade soul shield +1 more if its hard laning.

hoeray ranked wins!
Play defensive at start, farm as u can, dont spam your abilities & focus only on enemy champions. Personally i dont use spirit
blue buff: mantra + shield, hieling wave, healing wave, mantra + shield and so on.
U do need 60% mana for this, your HP doesnt really matter cos your shield is almost 24/7 up, and can healing wave yourself after.
Always stay behind in teamfights!!! or they will focus you first, once focussed your dead. but with good tank / players that aint an issue. You should always do mantra + shield on tank while he is initiating, do a healing wave, mantra + shield a dps or for an epic save.
Always buy wards(Whole team!!) so u can wards river/bushes. and preferably 2 or 3 ppl have teleport. so u can tele in and turn the teamfights your side. Don't waste a teleport to quickly save a turret from minons, you should arrive there sooner anyway. Also, if there is a teamfight and u die, when u respawn u can quickly tele in and your back in the game:).

stand in middle of minions, mantra + shield + healing wave = epic farm. after your deathcap its just mantra + shield :D.

The end off my Karma build. I might forgot something, so if you got any questions/sugestions or whatever, just post it in the comment section! Peace out!