|d20 Modern System Reference Document|
RESEARCH AND WEAKNESSES
Researching a creature and learning its weaknesses will increase the likelihood of victory in the ultimate confrontation.
A hero can uncover secrets about a particular creature or type of creature through research. The success of any such endeavor is measured with Research skill checks.
Researching a creature takes 1d4 hours plus an additional 1d4 hours if the creature is unique or has traits unlike other members of its species. The type of information gleaned in this amount of time depends on the hero's Research check result, as shown below.
Although a creature's type and species determine many of its traits and abilities, GMs are encouraged to alter a creature's physiology, behavior, abilities, tactics, and defenses when it serves the story or to confound players who think they know everything about their opponents.
The rules provided allow GMs to build custom monsters and ascribe special qualities to them. When designing a creature, the GM should also think of ways the creature can be defeated. From the heroes' point of view, a creature's weaknesses are more important than its abilities. Assigning weaknesses to creatures gives under-powered or poorly equipped heroes a fighting chance.
Table: Sources of Weakness lists many sources to which a creature may be vulnerable. A source can be a specific object, location, substance, sound, sensation, or activity. How the creature interacts with a source of weakness is left up to the GM, although most sources must be in close proximity to the creature (if not touching the creature) to affect it. GMs may roll randomly on the table, choose a source that suits the creature, or devise their own.
After determining a creature's source of weakness, the GM needs to decide how the creature reacts when confronted by the source. Pick an effect that seems appropriate for the creature and the source.
A creature gets either a Fortitude or Will saving throw to overcome or resist the source of weakness; the DC of the save varies depending on the source's strength:
Creatures usually react to a source of weakness in one of six ways:
Addiction: The creature is compelled to ingest, imbibe, or inhale the source. The source must be within 5 feet of the creature to affect it. On a successful Will save, the creature negates the compulsion. On a failed save, the creature spends a full-round action indulging its addiction, then may resume normal actions while suffering one or more of the following effects (GM's choice):
Each effect lasts 1d4 hours. Even creatures immune to mind-affecting effects are susceptible to a source-induced addiction.
Attraction: The creature is compelled to move as fast as it can toward the source. On a successful Will save, the creature resists the compulsion. On a failed save, the creature moves toward the source at its maximum speed, taking the safest and most direct route. Once it reaches the source, the compelled creature seeks to possess it. If the source isn't something the creature can easily possess, it gets a new save every round to break the compulsion.
Even creatures immune to mind-affecting effects are susceptible to a source-induced attraction.
Aversion: The creature finds the source repellant. On a failed save, the creature cannot approach or remain within 1d4 x10 feet of it. In the case of traveling sounds, the creature moves away from the source as fast as it can, stopping only when it can no longer hear it. On a successful Will save, the creature overcomes its aversion and may approach the source freely.
A repelled creature that cannot move the requisite distance from the source suffers one or more of the following effects (GM's choice):
Each effect lasts until the creature leaves the affected area and for 1d4 rounds afterward. Even creatures immune to mind-affecting effects are susceptible to a source-induced aversion.
Fascination: The creature finds the source fascinating and ceases all attacks and movement upon seeing, hearing, smelling, or otherwise perceiving it. On a successful Will save, the creature negates the fascination and can act normally. On a failed Will save, the creature can take no actions, and foes gain a +2 bonus on attack rolls against the creature. Any time the creature is attacked or takes damage, it gets a new save to negate the fascination. Otherwise, the fascination lasts as long as the creature can see, hear, smell, or otherwise perceive the source.
Even creatures immune to mind-affecting effects are susceptible to a source-induced fascination.
Fear: The creature is frightened by the source. If it fails its Will save, the creature flees from the source as fast as it can. If unable to flee, the creature takes a –2 morale penalty on attack rolls, weapon damage rolls, and saving throws. On a successful save, the creature overcomes the fear and can approach the source or otherwise act without penalty.
Even creatures immune to mind-affecting effects are susceptible to a source-induced fear.
Harm: Contact with the source or proximity to the source harms the creature in some fashion. On a successful Fortitude save, the creature negates the effect or, in the case of instant death or disintegration, takes damage instead. GMs may choose one of the following effects or invent their own:
Even creatures immune to effects that require Fortitude saves are susceptible to source-induced harm.