Well, Muzzleflashs are always cool, but I often see that people dont know how to make them, and I want to change that ;)
Lets get started!
Okay, open a new image, lets say 256x256 pixels
Now add some detail, also using the smudge tool
Now make 2 new layers and fill them with clouds , play around with the blending mode and opacity
Blending Mode: Merge
Blending Mode: Soft Light / Opacity: 55%
This is what you get
And now the last step: add color ;)
Make a new layer and set its blending mode to "color"
This is what you get in the end, now you see how very simple it is to make Muzzleflashs. It only took me a few minutes !