Hello.
I've tried many builds for Karma, but they didn't really work out for me.
So this is one i've come up with. The best thing about this build is that its very powerful, both defensively and offensively. Because of the good mana regen from the start i usually start helping the adc with the damage as soon as we start, and i never really run out of mana because of clarity and use heal if necessary. Sometimes i even end up with doing more damage than most of the other team, which in my opinion is a good support, for what good will an support that doesn't really do any damage be good? :D
Don't be afraid to use your ult and Inner Flame(q) a lot from early on, because it slows enemy champs if you hit correctly and it makes it a mental stress for them from the start.
I hope you will enjoy this build