I posted this before but since it's directly applicable and not in the thread TB indicated and wasn't originally in the HERO format, now reorganized/edited:
POSSESSION (STOP)
Type: Standard Power/Attack Power
Duration: Instant
Target: Target's DCV
Range: 5" x Active Points
Costs END: Yes
Cost: 15 Character Points for every 1d6 Possession
A character with Possession can "inhabit" a target, directing its activities and subsuming its identity. Examples of Possession include a demon that inhabits a person, a program that takes over a computer system, and a brain which may be transferred to any number of suitable hosts.
BUYING POSSESSION
While the cost of Possession is fixed at 15 points per 1d6, upon purchasing Possession the power must be declared as working against Body, Mind, or Spirit (see "Body, Mind, and Spirit" below); every time the power is used, it may only work against this one declared type of Possession, it may not be changed. Additional types of possession may be purchased and thus combined (see "Advantages and Adders" below).
Unlike other powers, Possession may also be bought at time of purchase to work against BODY or EGO in applying the "damage' of the Possession attack. However, it must be bought for one or the other only and may not be changed later or according to target.
Note that there is no necessary/intrinsic relationship between which type(s) of Possession (Body, Mind, or Spirit) is chosen which characteristic the Possession will be declared to work against (BODY or EGO).
USING POSSESSION
To use Possession, the character makes an Attack Roll. If he succeeds, he rolls the Possession dice, and subtracts the target's Power Defense (if any). If the remaining total is equal to or greater than twice the target's starting characteristic as chosen at time of power purchase - BODY or EGO (i.e., the BODY or EGO he has when fully healed) - the target is Possessed.
If the total is less than twice the target's starting BODY/EGO, he suffers no ill effects from the Possession... (note, this should just follow the same basic verbiage of Transform up until the example, where it begins to deviate)...
Example: Vampiros purchases a 7d6 Possession (possess Spirit and Body, against EGO). This costs (6 x 15 =) 115 Character Points. He later attempts to use his Transform against a target with 20 EGO, and 3 points of Power Defense. On his first attack, he rolls 22 "BODY", which does (22-3 =) 19 BODY of Possession "damage' to the target. Since this is not equal to or greater than twice the target's EGO, the Possession does not occur. On his second attack, Vampiros rolls a 25, causing (25-3 =) 22 "BODY" of Possession "damage" to the target. Although this is not equal to or greater than twice the target's EGO by itself, it adds to the existing 19 points of Possession "damage" for a total of 41 points. This is at least twice the target's starting EGO, so the target is Possessed by Vampiros.
When Possession does not succeed completely with a single attack, the effects of the incomplete Possession "damage" can be perceived according to the SFX of the Possession. To use the Vampiros example above, Vampiros' first attack caused his target to change facial expression as he thinks dark, horribly heinous thoughts (the effect Vampiros exudes when he takes over someone's Spirit). This causes no game effects - no loss or alteration of Characteristics, Powers, and the like (not even Comeliness) - but does alert the target as to what's going on.
Because Possession only remains in force while the possessor remains "in" the target, "damage" done but not followed through by a successful Possession dissipates quickly. The Character Points mitigating the "damage" return to the target at the rate of 5 Character Points per Turn. Unlike with Adjustment Powers, the rate of return is not usually allowed to be altered with the Delayed Return Rate Advantage, however, this Advantage may be applied with GM permission.
BODY, MIND, AND SPIRIT
Possession, like Transform, has 3 targets - Spirit, Mind, or Body. Spirit possession indicates the person's drive, goals, and emotions change (essentially) but they are intellectually and physically the same person, they don't know that something else is controlling them. Mental possession is essentially like a brain transplant; the target is essentially a shell for the new mental presence, and the new mental presence has none of the knowledge/mental skills of the target given they are displacing those abilities. Body possession means that the body itself has been altered or changed somehow, and the new being may possess the mental and spiritual components of the original person, but those have been fused and over-ridden with a controlling presence that is physically manifest in the person. Of course, there can be crossed forms; although we may think of vampiric transformation as spiritual, it has both a body and spirit component, typically with only the memories and knowledge intact.
Each possession of course allows the possessor to control the target, but important nuances apply for each form.
Spiritual possession allows the possessor to have full control over all facets of the target, however any mentalist may Mind Control the target to resist the possessor, and mental commands with the target's "original" self are allowed; however, the mentalist must reach the subconscious level of the target as that is the only level remaining in the possessed form. Also, the target's Psych Disads remain intact and the Possessor must make an EGO vs EGO roll to overcome any hesitation by the possessed to perform as desired.
Mental possession also of course allows for full control but as the mind itself is switched, all INT and EGO based skills are not available to the controlling party. Importantly, the memories and knowledge of the target are also displaced, as are all Psych Disads. This does not mean the possessor may not leverage powers and the like; it is presumed that the possessor will learn the body's abiltiies after "reaonable" (per GM, SFX, and the power constuctioN) time. However, unlike Spiritual, the mind of the target is gone and may not be reached by Mind Control or other means.
Body possession allows the possessor to physically control the body entirely, without mental or spiritual inteference. However, without Telepathy or other skills, the possessor is not necessarily aware of the target's abiltiies. Like with spirit, the mind of the target may be reached by any mental means by others, but unlike that, only superficial contact is necessary as the mind is fully aware and intact. It is important to stress that unlike with mental and spiritual control, there is no way for the possessed to act physically independently, even if their mind may so act, regardless of Psych Lims or such. The possessor, though, may not apply any abiltiies which require the specific knowledge or mental skills of the target, much as with mental possession. A very important difference with body possession is that whereas both spiritual and mental possession do allow the possessor to be targeted mentally (instead of the possessed, in the case of spiritual possession), this does not apply with body possession. The possessor's mind is not specifically/necessarily linked in a way that it can be targetted, providing a particular advantage to physical possession.
Mixing these forms gives the most advantageous of each, except that when combining mental or spiritual with the body form the possessor may be targeted mentally.
It should be noted that in order to properly apply the powers of the Possessor to the Possessed target, the Possessor simply needs to use the normal Usable by Others Advantage with any powers he wishes the Possessed target to use.
BREAKING OUT OF POSSESSION
To break the possession, normally Dispel or a similar Adjustment power would be used. However, both mental and spiritual forms grant additional methods of breaking the possession. With either, the possessor may be (assuming sufficient power is applied) Mind Controlled into depossessing (normally this would be considered an action the possessor is violently opposed to, although of course SFX and common sense should apply). WIth the spiritual form, the possessed target may overcome the possessor if assisted with an EGO vs EGO roll; for this to happen, the mind of the possessed must be reached either via Telepathy or some similar circumstance. Once reached, it may simply be triggered if the possessed is willing to attempt to break out, as this represents the "waking up" of the possessed consciousness. Naturally, most often, the possessor will ensure sufficient EGO to overwhelm targets. Other characters may assist the possessed so long as they have Telepathy or Mind Link to the possessed by adding their EGO rolls as Complementary rolls.
Depending upon genre conventions and campaign needs, the GM may also impose that a Possession must have (whether in addition to or instead of the above) an all-or-nothing method by which the Possession may be broken.
ADVANTAGES AND ADDERS
Multiple Types of Possession: Each additional form is a +10 adder to the total cost (not per dice); even if all 3 forms are taken, there must be some sort of weakness or "opening" for the possession, some link back to the original person. Even in cases where one may employ Possession against Body, Mind, and Spirit, there must be some sort of weakness or "opening" with which the possession may be undone, some link back to the original possession. The GM must approve any multi-type Possession and agree as to the SFX, including the weakness for a Possession against all three types.
Possessing Multiple Targets: When possessing a target, the possessor has no control over any former or native body they may normally or previously have had. Normally, possessors are bought with a normal native body or as figures that have no corporeal body (with appropriate Disads and possibly Desol or EDM to represent that state); in either event, they may return to their native form simply by abandoning the possessed form, but once that happens, they must perform the Possession over again. To freely switch between forms is a +5 Adder for every x2 forms they may Possess. For example., for +5 they may switch between one other possessed form (presumably the most recent, although this should be dictated by SFX and power definition) and their native form only, with no other forms/possessed being possible to switch among without performing the Possession Attack again on them (and in that case, their other possessed form would then be dropped from this "pool"). For +10 (instead of +5) they could possess up to 3 other forms plus their native form, switching among those. It should be noted though that possessed forms do revert back to the control of the original target as soon as the possessor switches away from them. For a +1 Advantage, the possessor may render all other forms into a catatonic or similar state when not directly possessing them. For a +2 Advantage, with GM permission, the possessor may actively possess all forms at one time.
Copious examples are required, but that's all I'm up for doing now as that took longer than expected.
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