Harvested souls can be used to invest in powers and strengthen them. Powers in question can be used on downed enemy girls and onlookers can become terrified into a stun effect. More invested souls equals longer stun.
Unsure however is whether gore would be a lesser or greater power, seeing how much easier it is to gib in real life compared to impossible fetishes like rearranging limbs, full body inflation without a pop, or headstealing, without killing the victim.