From the Introduction:
This web-exclusive supplement to The Soul Reaver provides new options for Dark Eldar Explorers that players and Game Masters alike can use alongside the Kabalite Warrior Career Path featured in the main volume to explore new facets of the insidious Dark Eldar. This supplement requires a copy of the Rogue Trader Core Rulebook for use.
These new options include the Wych Career Path, for players who wish to take on the role of these elegant and brutal killers. Unlike Kabalite Warriors, who focus on inflicting suffering at range, Wyches are artists of the arena, melee combat specialists who do their dark work up close. To them, a dying breath is not a whisper heard from afar, but a billowing breeze that stirs around them each time they kill.
Further, it contains three Alternate Career Ranks to help players construct iconic Dark Eldar characters. The Skyterror is a master of aerial combat, the fiendish Fleshcrafter Disciple twists bodies into terrifying new forms, and the Incubus Initiate relentlessly pursues martial perfection. With these deadly tools in hand, we hope that players will go on to create unique Dark Eldar characters to overcome deadly challenges, reap vast and terrible rewards, and shake the Koronus Expanse to its very core.