I'm currently learning krakatoa and I wanted to share with you some stuff of what I learned. It's a basic setup :

a pflow source from my previous fumefx sim (the horse) and I used this pflow source and partition it 10 times to get a high amount of particles (approximately 90 millions but with the delete operator on the pflow source I'm not quite sure about the real number) then with the prt Loader I add the magma channel data editing to add a more interesting look, for this example I mainly use the velocity of the particle to drive the color and add a gradient map as a texture for the particles and finally add some absorption to the all thing.