QUOTE (Teegster @ Oct 27 2009, 05:01 PM)

1) Is it possible for a player to possess while he is astral?
A caster with a Possession tradition can summon spirits who can possess creatures/items. After summoning, they arrive in the astral plane. For them to affect the physical plane they must possess an object (creature/item.) That takes a complex action, a service, and may require a possession test depending upon the target. The spirit then controls the object it possessed if successful on the test.
For a player to do these things, they would probably need to be a free spirit from a possession tradition. They could also be a mage with the Invoking metamagic, a possession tradition, and access to spirits with Endowment great form power (Guardian or Task.) If the mage invokes a spirit via binding and gets 5 or more hits on the Invoking test, the spirit will have the Endowment great form power and can grant any of its powers to another person including its Possession power. If the mage then astrally projects they would be able to use the Possession power from the astral plane in the same way as a spirit.
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2) Can a spirit possess a rigger while said rigger is in one of his machines?
Yes a rigger who is Hot Sim controlling a machine is still wholly present from a body/soul standpoint so it would be susceptible to possession just like any character. They would lose their link to the machine as a result because the spirit would not have access to the rigger's skills to control the machine.