It doesn't really seem like you changed much about her. The problem is she has level six mana costs on her level six abilities while doing level five damage. The change to her W would be nice, except if your going to make her ultimate only available at lvl6 AND unaffected by cooldown reduction, it turns out to be a major nerf to her. You would have to make the mantra charge do something more to each ability if it is unaffected by CDR. Even with three charges she would use all of those charges up in a teamfight, then sit around and be a meatsheild for 15 seconds lategame, which is not how she plays out now nor how she should be played.
What Karma really needs is to have her abilities scale more sharply in damage per level or have some sort of added effect at six (regardless of a mantra charge, perhaps similar to syndra's passive) or have the mantra charge do more to her abilities, because currently she has no crowd control (even a simple knockup would be nice) and her W does not feel strong at all now, and even if the numbers were buffed on W, the positioning required to use it is awkward and often puts Karma in danger. No other speed boost/slow does this.
So, in conclusion, she needs her abilities to scale more sharply per level, she needs some sort of crowd control (with or without mantra) and she needs her W to be looked at in terms of positioning/function.