Karma was an old character who appeared a few times in Marvel Team-Up. She was similar to Xavier. She basically had the power to control someone's mind from a distance and then control their body. For instance, she took over Spider-man's mind and had him fight the Fantastic Four, controlling all of his powers and abilities. She has the capability of making someone kill themself, thus the 'can Hulk kill himself' question. I have no idea whatever happened to her.