Usually I think of immunities as being a protection from things that other creatures may try to do to the immune creature. Not for protecting against things that the creature tries to do to itself. So casting Sleep on an Immortal Ichor is not going to work, but the unconscious condition applied by the Immortal Ichor using Possession probably should.
Also it seems like a bit of a gimmick to have a partial effect work. If the creature is immune to an effect, the entire effect is negated. Only if a spell or ability has multiple different effects should some of the effects be functional and others get negated. I think that is the best ruling in line with the Immunity rules. So for Possession that would mean that the sensing and control of the other creature is part of the same effect as the unconscious condition of your own body. If you want to be immune to unconscious, you can't also get sensory input or control of a different body.
It seems that the body would go unconscious while the Ichor inside says "Crap, I should get out of this useless shell."
It seems that the body would go unconscious while the Ichor inside says "Crap, I should get out of this useless shell."
That's not how the Possession spell works. At least that is not how I have been reading it. The caster's body becomes unconscious, but the target's body does not. It instead becomes partially or fully controlled by the caster depending on the results of the saving throw.
It seems that the body would go unconscious while the Ichor inside says "Crap, I should get out of this useless shell."That's not how the Possession spell works. At least that is not how I have been reading it. The caster's body becomes unconscious, but the target's body does not. It instead becomes partially or fully controlled by the caster depending on the results of the saving throw.
That's the casting portion, on which we agree.
I'm talking about when an effect causing direct unconsciousness hits the possessed body. Even though the Ichor (as possessor) is immune to that condition, I'd think the target body wouldn't be.This ties back to the (not delineated) metaphysics of Golarion. Is Unconscious a condition of the body/brain or the spirit/mind? One clue would be whether casting Possession on an Unconscious target wakes the target's body up or not. And the answer might also depend on the source, whether it's physical trauma or a spiritual attack causing the Condition. And is the Ichor immune to Unconscious due to the nature of its body or the nature of its mind?
Ah. Yes, casting Sleep on the possessed creature probably should work to put the non-unconscious-immune target down. And yes, at that point the possessing caster will likely dispel the magic and go back to their own body.
I'd probably even allow that even if the caster isn't immune to unconscious. But that is more debatable.