I decided to make this guide as my first...and probably only guide...because i couldn't find any others out there. karma's description says she is support so people are fooled into thinking she is support. when playing karma it is best to ask if anyone likes the solo lane before locking in. if they do, simply pick a new character...if they allow you the top/middle lane, proceed in causing your opponents to nerd-rage about how OP Karma is.

reasoning behind build in equation form
solo lane + delaying spirit bond + buying mana Regen first = obliterating minions early = early money = AP before opponents buy resist = kills = money = win

early mana from meki pendent will keep you in lane and morello's tomb which yo will form it into is pure AP and spell reduction...the core of this build.

if you are week and need to buy the 2 speed boots to run...there is no shame in buying them before the second wand

the tomb and boots combo will give you plenty of CD reduction...after that you want AP up the wazoo starting with the almighty deathcap...don't worry about being squishy, more AP = stronger heal and shield

once you are destroying everyone...make it a little easier with a couple scepter's...

1) abyssal should come first if any of the enemies are AP based unless there is only one and he/she is a supernoob...along with the resist...abyssal reduces enemy resistance from you =)
2) rylai's should come next for a little extra health
3) void staff will ensure that your damage is not resisted while adding more Delicious AP

after that the choice is yours...i prefer to go banana's with AP, but if u like killing people in 2 shots while being invincible instead of 1 shotting...be my guest

the 9 points in the damage tree is obviously there because when going for AP obliteration...archaic knowledge is essential (+15% magic pen)

going into the defensive tree allows you to be surprisingly tankish without waiting your money on defensive items

the nimbleness talent stacks well with dodge runes...AP and magic pen runes are there for obvious reasons

the speed quintessences are purely my preference...I'm sure CD reduction or ability pen are also very viable...but i don't think they are necessary with the items I buy

i avoid spirit bond early in the game for 3 reasons

1) it is not necessary to slow an opponent you cant kill (yet)
2) powerful shield and fan keep your opponent scared
3) MOST IMPORTANTLY you can one shot every enemy minion in less than a second...early minions = early gold...you should be able to one shot minion waves at about level 6... getting there fast will give you a massive advantage

--KILLING MINIONS IS ESSENTIAL--
to efficiently own minions follow these steps
1)hit mantra
2)charge in and disregard opponent (unless there are multiple)
3) explode your shield hitting all minions
4) retreat and fan blade yourself a bunch of cash as your opponent finishes off your shield leaving you with the same health you started

if there are no enemies... push past your minions and run halfway through the enemy minions and move to the side. they should be in a nice arch for you to fan blade...eventually this will not be necessary because shield alone will kill them

things to remember

1) you are not OP at the beginning...pressure is good, but don't try to get a risky kill
2) you still suck even though you can 1 shot minion waves...
3) once your leet monion owning skills give you mad damage...don't be afraid to help your teamates...(you are supposedly a support character)
4) if you kill most of the enemy team do not help the push...kill more minions...it is more effective in the long run