According to the description this allows you to "extract a victim’s soul from his blood and capture it in a vessel of some kind". It also says "if you want the victim to remain in the vessel for ever"
Sounds like something that could really spoil the victim's day, but what is the intended practical effect? Can they function without their soul? Are they in some sort of Sleeping Beauty type coma? Or is their physical form confined in the focus as well?