I have been working on developing a magic system very similar to this. Mine is based around eight "core" emotions.
Love and Anger
Joy and Sadness
Hope and Fear
Pride and Shame
I think I will keep them grouped in pairs for now. Although, I don't really know the limits or actual powers and abilities for different emotions. I am also having trouble figuring out the downside, as well as how severe it should be. Where my mind is going at the moment is possible colors for different emotions. I think in mine, you will have to have complete control over the emotion you are trying to conjure.
Just an FYI. In my world, magic has almost completely died. It is extremely rare and forbidden. Those who do possess the ability keep it hidden.