And a perfunctory edited version, pending your thoughts.
Foxfire [-4]
Description: A gift from the fox spirits of legend allows you to cloud minds, fool the senses, and even drive people to insanity.
Sponsor: The fox spirits of Eastern legend, AKA nine-tailed foxes, huli jing, kumiho, kitsune, and many other names. Contrary to many modern interpretations, fox spirits tend to be unrepentant monsters with a taste for human flesh, though benevolent individuals exist. Many scholars compare the diversity of fox spirit myths to faerie lore in European traditions, though the two are (probably) distinct supernatural genera. Fox spirits are often worshiped, or at least placated, in traditional shrines.
Agenda: Seduction, illusion, the gaining of status and wealth through dishonorable means or Faustian bargains. Foxfire prefers to be used in indirect ways, but when grave insult or disrespect is offered, it kindles brightly with the desire for vengeance.
Evocation: Foxfire evocations are often limned in ghostly blue or red flames. Foxfire employs raw spiritual energy channeled in the form of voracious insubstantial fire It is quick to take hold and consume, but just as quick to burn out or be quenched.
Thaumaturgy: Foxfire can be employed to manipulate emotional states, create durable illusions, and to cause effects in a target household that resemble a haunting or demon possession. When used offensively it has a the unique preference for inflicting mental stress, the fire that burns cold but sears the soul.
Evothaum: Foxfire allows its user to cast Photomancy and Psychomancy with the speed and methods of Evocation.
Extra Benefits: When using foxfire for maneuvers that cloud or deceive the senses (illusions, maneuvers to inflict certain consequences), the spell gets a number of free extra shifts for duration equal to the caster's ranks in the deceit skill. The original maneuver must still be successful for this to take effect.
Tell me if you think the new extra benefit is trying too hard to be clever.