Source: MtAw core book p317
Instead of the nine Attributes used to define creatures in the physical world, spirits have just three: Power, Finesse and Resistance.
Power represents a spirit’s raw impact on the spirit world, through force of will or its form.
Power is used for all rolls that would normally involve Intelligence, Strength or Presence.
Finesse represents how well a spirit can manipulate other spirits, people and its environment.
Finesse is used for all rolls that would normally involve Wits, Dexterity or Manipulation.
Resistance measures the strength of the idea behind a spirit and how easily the being is damaged and influenced by others.
The spirit’s Resistance is used for all rolls that world normally involve Resolve, Stamina and Composure.
Rather than Health, a spirit has Corpus dots that represent the resiliency of its ephemeral form.
Corpus dots equal a spirit’s Resistance + Size.
Spirits regenerate Corpus in the same amount of time that mortals heal damage (see the World of Darkness Rulebook, p. 175).
If a spirit loses all of its Corpus, it is discorporated.
If it loses all its Essence and Corpus, the spirit is destroyed.
A spirit’s maximum Essence is determined by its Rank (see “The Spiritual Hierarchy,” below); any given spirit may have any amount of Essence up to that limit.
Spirits must harvest Essence from sources whose resonance is related to their natures.
The lower a spirit’s Essence is, the more desperate it grows for sustenance.
Spirits have a Willpower trait that’s used as normal.
A spirit’s very existence necessitates a certain will to survive and grow.
Most spirits regain spent Willpower at the rate of one point per day, though the rate increases if a spirit is particularly successful at harvesting Essence with an appropriate resonance.
Spirits possess Initiative, Defense, Speed and Size as other entities do.
Initiative is equal to Finesse + Resistance.
A spirit’s Defense is equal to its Power or Finesse, whichever is higher.
Speed is equal to Power + Finesse + a “species factor.”
Spirits that take human or animal form have a species factor equal to their earthly counterparts.
Spirits of inanimate objects usually have a species factor equal to zero (save for spirits of cars and other objects designed to move quickly), while spirits of more abstract form generally have a species factor of 10.
A spirit can generally be of any Size, depending on what it represents and how powerful it is. Exceptionally strong spirits are often larger than their weaker kin.
Note that spirits do not possess either Skills or Merits.
A spirit suffers no penalty for untrained Skill use, however, as long as the task is appropriate to the spirit’s area of influence.
A spirit of information can rifle the database of a computer using Power + Finesse alone, without suffering the usual – 3 penalty for attempting what would ordinarily be a Computer
task without actually possessing the Computer Skill.