Intellect Devourer and Phrenic Scourge

[Darkild]

1. Is it possible for an Intellect Devourer to inhabit a human body for more than 7 days(20 years to be exact) and maintain full usefullness of the body/keep the body from decaying?

2. Phrenic Scourges - for them to enslave someone, how would they do it, how much time would they need to do it and do they need to maintain some sort of focus for the enslavement to continue working?
(it as a combination of Charm Monster, Detect Thoughts, Suggestion and their psion ability Sap?)

3. Phrenic Scourges - Can you become immune(even momentarily) to their psion attacks/enslavement attempts?

[VRMH]

1. Use the Gentle Repose spell - I think the creature's write-up already mentions it. If you see the host body as an object, you could argue that Mending works too.
2. Enslavement can be magical - Domination or Geas, or a whole bunch of stacking Hypnotisms. Or it can be mundane: chains, whips and intimidation checks. I suppose either way it wouldn't take more than a few days to gain total control over all but the most strong-willed individuals. Much depends on how much control the Phrenic Scourge wants.
3. If you're immune to mind-affecting effects, I guess you would be immune to their Sap Will ability - even though it's not marked as [mind affecting]. There may also be ways to become immune to psionic attacks specifically, but I don't know the system.

[Skylancer4]

#3: Globe of Invulnerability