Its simply an HG Woma crossed with a Lesser.
http://www.ball-pythons.net/forums/s...d.php?t=122970
The HG Woma is a totally different morph from the Woma (both of which are basic one gene morphs), they saw it, figured it was a Woma, then noticed it made ridiculously awesome snake when bred to things, they guessed it was a Hidden Gene, but in the long run it turned out to be just a simple basic gene (1 gene not 2).
The Soul Sucker looks so fantastic because the HG Woma morph is just a fantastic genetic morph that reacts in amazing ways in designer morphs.