Demonologists get their powers from consorting with demons. Demonologists have three ways of using demons to perform magic: as familiars, by performing rituals to summon them and strike a deal or compel them to perform a service, or by forming a permanent pact. Demonologists may take the Arcane Familiar Edge multiple times. The Demonologist may only take Power Edges if there is a pact with a demon, and those Edges are actually applied to the demon (so if the demon is ever exorcised, the Demonologist loses them).
Arcane Skill: Spell-casting (Smarts)
Starting Power Points: 10 (these are actually the demon’s points and are lost if the demon is ever exorcised)
Starting Powers: 3 (see above)
Demonologists can take a normal animal and bind a minor demon to it to serve as a familiar. Use the Arcane Familiar (AB:Magic) rules from the Fantasy World Builder Toolkit. The familiar has no special demonic powers other than the ones described in the Familiar Edge.
The key to most Demonologists power is the pact they form with a particular demon. This allows the demon to dwell within them, and for them to use the demon’s powers as their own, but it comes at a price, namely the risk that the demon will take them over, either temporarily or permanently.
All demons have one Attribute: Spirit. Their Spirit is determined by the Rank of the demon, from d4 for a Novice to d12 for a Legendary demon. All demons have one Major Habit; this is a vice that the demon will try to indulge in to the maximum extent possible if it ever gains control of the body it shares with the Demonologist. Demons do not get Bennies when they are in a pact with a Demonologist. The GM may choose to create stats, skills and Edges for the demon, in case it ever manifests physically, but while the demon is inhabiting the body of a Demonologist, they are irrelevant. All Demons are also Wild Cards and get a Wild Die on their rolls.
As an Action, the Demonologist may force his demon to use one of its powers. Roll the Demonologist’s Spell-casting die without the wild die. On a roll of a 1 there is Backlash (the demon tries to take control), otherwise the demon will use the power as directed (roll the Demon’s spell-casting die and wild die). The Demonologist may spend Bennies normally on the Demon’s spell-casting roll.
On a roll of a 1 on the Demonologist’s spell-casting die, the demon attempts to seize control. The Demonologist now makes a Spirit vs. Spirit test against the demon. If the Demonologist loses, the demon takes control. Regardless of the outcome, whoever is now in possession of the body is Shaken.
Once a demon takes control of the body, it will remain in control until it sleeps, or it gets a 1 on its casting die (which causes another struggle for control). If the Demonologist botched the spirit test in the struggle for control, then the demon may remain in control even if it goes to sleep, though it will still have to struggle again if it gets a 1 on its casting die. While the demon is in control, the Demonologist has no awareness of what is going on in the outside world.
During the time when the demon is in control, it will attempt to indulge in its favorite vice to the exclusion of all else. For instance, if it craves alcohol, it will wander off in the middle of a battle in search of a drink. It will defend itself if directly attacked (because the pact forces it to), and avoid placing itself in obvious immediate danger (sitting down in the middle of a stampede to have a drink), but it cannot or will not consider the costs and benefits to anybody else of its actions or voluntarily defer gratification for a greater reward later. A character can make a successful Persuasion roll to bribe the demon, but demons don’t consider themselves bound by any promises that aren’t magically reinforced, so it won’t stay bribed if it spots a better opportunity. The demon may or may not choose to try to hide the fact that it’s possessing the Demonologist, depending on its past experience; if every time it’s gained control in the past, the Demonologist’s companions have tied it up and knocked it out, it will pretend to be the Demonologist at least until it can sneak away. If the companions don’t seem to be in any position to stop it from indulging itself immediately, though, it won’t engage in a long charade unless it’s particularly cunning.
Because control reverts to the owner of the body when the demon becomes unconscious, demons will do everything that the setting allows to avoid falling asleep until absolutely necessary.
Demons and Experience
Whenever the Demonologist gains an Advance, he may choose to improve the demon by taking a Power Edge that applies to the demon. Whenever the Demonologist goes up a rank, the demon’s Spirit attribute automatically advances a die.
If at all possible, the GM should let the player still play the character while the demon is in control, since otherwise the player can be left sitting out a significant portion of the game. If the GM doesn’t like the possibility that the player’s character will not regain control of his body even after the demon has to sleep, remove the effect of a botch on the Spirit vs. Spirit roll. If that’s still too long, you could allow the player more frequent attempt to break out, but you might want to reconsider letting players take AB: Demonology in the first place.