Elf Mind-Rend (Patreon)

There exists a spell under the Influencer group that allows the caster to forcibly wrench the target's spirit and willpower from them, resulting in them becoming an empty vessel or puppet of sorts - becoming completely obedient to the one who has taken their spirit hostage. The consciousness is stored in a type of dimensional prison for the length of the effect. 

Every action has an equal reaction, this is something the mage schools know well. Creatures that have a natural inclination for Influencer magic - like succubae, sirens, or harpies, are in turn easily affected by such spells. Creatures like elves, which have a lower-than-average resistance to magic, also find themselves unable to resist spells which influence other beings.