The Karma buff just exemplifies her dependence on Mantra to be useful
Its not that I don't think she needs a buff or two, but it really just shows she's too dependent on Mantra to be useful to her team.
Mantra E (and Mantra Q if mid) is/are pretty much her entire kit at this point and they're not even allowed to be that powerful because of her passive.
Her Passive lets her get Mantra back up so often that her Mantras can't be that strong.
I'm not saying she's bad (or that Mantra E is bad either,maybe for overall Balance health but that's another topic) but she's just too reliant on Mantra to be useful, which has to happen because she gets it up so often otherwise her base abilities would be too good while also having mantra.
I do realize that she has a kind of mini rework (if I understood Meddler correctly) planned in early 2017, but this just pushes forward the main problem with Karma.