Fiery Effect

[His Greatness]

Does anyone know how to do this awesome fiery effect like in the following sigs:

 

[Project]

I pretty sure its just an abstract brush.

 

[The Marine]

yeah, it is a brush. not sure what one tho.

 

[dc42315]

I've been looking for a brush like that for a long time, still haven't found one, I would love to know this as well.

 

[ortiz34]

If anyone finds the brush, can they post it or something? Would be real grateful, it's an amazing effect.