Karma's Q base damage seems a bit high for an AoE on a 5 sec cooldown...
80 / 125 / 170 / 215 / 260 (+60% AP) Considering she doesn't even have to HIT you to deal damage, and she can just Q the minion wave to get free harass. You can't even stand behind minions when fighting her. And considering she's a semi-support sent mid/top lane, I think this could use a nerf. You could reduce the damage to start, Or the AP ratio, Or just increase the cooldown.
Honestly the late-game power is okay but early to mid game it's really unfair and makes it nearly impossible to win lane especially if she's into a melee matchup. So I would decrease base damage and increase cooldown so: 50 / 90 / 130 / 170 / 210 (+55% AP) on a 10 / 9 / 8 / 7 / 6 sec cooldown. Slightly lower AP ratio, lower base damage, and increase cooldown.