Okay, so I KNOW this has probably been asked before, but searching through literally thousands of pages on dumpshock for the answers I seek is not my idea of fun.

So, as a GM, I am going to start a story arc involving a rash of spirit possessions. However Street magic is somewhat vague on the particulars however, and I'd like some answers before I start sending my players in.

1)If a spirit has complete control over a body (either they have made a pact, or done the bug spirit possession thing) what does a Mage see when astrally assensing? How many successes would it take to see the spirit?

2)If the host body is killed, what happens to the spirit?

3)What powers does a spirit possessing a body have? I know that each spirit bestows a specific power (such as the Mantis ability to eat other bug spirits), but does the spirit get to keep any of it's other powers? If, say, an air spirit possesses a human, can that spirit then fly as a human? Or can a human-possessing water spirit breathe underwater?

4)If a spirit possesses a human, does that human show up as magically active? Like if you took some of that magic-detecty moss and put it near a bug spirit-possessed human, would it light up? Are they dual natured?

5)Do spirit-posessed metahumans automatically get two IPs? Because a normal spirit acting in the real world gets 2 IPs, so I dunno.

1) Possessed People and the spirits possessing them are one merged entity. You see the dude/spirit-combination. It's impossible to "overlook" the fact that the person is possessed while assensing. Keep in mind that it's basically impossible to overlook that fact by simply looking at him regularly, as well.

2) It's disrupted.

3) All the powers it has normally. Spirits neither gain nor lose any powers just by possessing someone.

4) That "human" doesn't, but the merged entity is't now part of is not only magically active, but dual natured (so it can't even turn that off).

5) The spirit has two IPs. If it's the spirit controlling the dual entity, the entity has two IPs as well. If the possessed person controls it (like a summoner using Channeling) he has as much IPs as he usually gets.

You're talking about Possession, but mention Bug Spirits, who don't have that power, but use Inhabitation instead. Those are not identical.

Thanks for the answers, but now I have a few more . . .

1)What is the difference between An "Inhabited" dude and a "Possessed" dude?

2)


Spoilers for ghost cartel:

Possession spirits with the Aura Masking power can conceal their nature.

1) Spirit pacts don't usually result in possession and bug spirits inhabit a person, they don't possess. Posession is something that a spirit can do in a complex action, requiring a Force x2 test vs its victims intuition + willpower, and it can only be forced out by a banishing test. Assensing would be easy, a threshold of 2 is necessary to determine an object's class as "spirit," although because of the entity's dual-nature they'd be constantly active on the astral plane, which is noticeable without a roll. Recognizing posession on the physical plane requires a perception threshold equal to 6 minus the possessing spirit's force, although this can be modified however you want as the GM, I know many prefer to have possession be immediately obvious if the spirit doesn't have realistic form
2)More specifically, the spirit is expelled from the host body with damage equal to the total damage taken while posessing. Usually this is greater than the spirit's normal physical damage track, and would cause disruption, but if the spirit is one of earth or beast it may have a higher Body when not possessing than when it does have a host, if the host has a low Body, because the spirit adds its force to its hosts physical attributes, not its actual stats.
3) A spirit when possessing gains all of its spirit powers, however, it cannot fly or breathe underwater or use the movement rates listed for spirits it the main book. This is because those rates are listed for Materialized spirits, not possessing ones, and are not Spirit Powers. Actual spirit powers are listed under the powers section, and are for example, Movement, Guard, or Elemental Aura.
4) As has been said, Possessed entities are dual-natured and are obviously magical on the astral plane (although not necessarily obviously possession spirits). The magic detection moss does not work on possessed beings however, as it requires the moss to pass through a spirit on the astral, which would require it to pass through the physical body of the possessed entity, so unless you stab the possessed person with your moss rod, your not gonna be able to use that for detection.

Inhabitation is different from possession in that it is permanent, and the inhabited being dies after being inhabited, as opposed to becoming a helpless witness while being possessed. Inhabitation also takes a matter of days to complete, and requires a third party magician to do it. Inhabitation can take 3 forms, true form, hybrid form, and flesh form, which are detailed on p.100 of Street Magic. Basically, true form makes a permanent Materialization spirit, Hybrid form makes a permanent and more obvious possession spirit that can use a neural interface, and flesh form makes a spirit who looks, talks, and acts like a person, has a person's attributes and skills, but the spirit's mind and motives. Most Inhabitation spirits are going to be Hybrid Forms, while weaker spirits will be more subtle flesh forms and stronger spirits will be the most obvious true forms.

If in your campaign a player becomes in danger of being inhabited, keep in mind that inhabitation can't actually fail(unless the spirit critically glitches), once the casting is finished the host is dead and his body is that spirit's new home. A player's resistance roll only determines what kind of inhabitation the spirit gets, so if the player rolls 9 hits to resist and the spirit rolls 0 (without glitching) that spirit still takes over the host's body (as flesh form).

Patrick explained the Possession/Inhabitation difference well.
As for the Ghost Cartel spoiler: