Wrong. Anyways, it's pretty easy, since the dark flames colors (if it isn't a blending one) uses almost all the rgb scale, and alpha imperial is pretty blue-black, you can manage it pretty easily.

For void flames, if you want a green flame, just set a red particle flame. In your case you will need to do something similar, but with some limitations.

I am not as good at art, but it's easy when you know something of colors coming from physics in the univ ;D