Thank you to everyone who commented; this is not exhaustive, and if I missed a point, let me know. First draft, and all that.
Crunchy bits in Poughkeepsie
Celestial Form: cannot be manifested or maintained. The Bubble forms an impenetrable barrier to
those in celestial form.
Dissonance: It doesn't happen. Dissonance carried into Poughkeepsie comes back out, but no celestial actions inside the Bubble will cause
This does not necessarily please celestials; indeed, it unnerves quite a few of them. Dissonance for a celestial comes from too-great a breach between what an angel or demon is and what they should be, according to either Choir / Band or Superior Word; to have this suddenly go away is profoundly unnatural. Many celestials may fear and hate dissonance, but they also recognize that dissonance restrictions make up a significant portion of their very souls. Of course, some celestials will embrace this unnatural state of affairs, or at least take advantage of it if absolutely necessary. But that is a far cry from finding the condition normal.
Of the myriad reasons why celestials find Poughkeepsie unsettling, the above is probably the most self-evident.
Death: Ethereal and Celestial combat is impossible from inside of Poughkeepsie; all combat is corporeal. A regular human that dies inside the Bubble becomes a Ghost without a focus, which essentially means that he or she cannot do anything but drift near the place of death. Fortunately, souls apparently have a bare hint of physical existence: given time, the soul might drift to the edge, but will probably be caught first by some of Lightning's specially designed ghost traps. Once the Ghost leaves the Bubble, it will go on to Heaven, Hell, reincarnation and/or dissolution as normal.
On the other hand, a human who would normally become a Ghost
anyway will automatically become one; the Ghost cannot spend Essence, but will
be able to move around freely inside the Bubble and make sounds that can be
heard on an absolutely unmodified Perception roll. A Ghost created in this matter will not have
a Focus, which means that leaving the Bubble will automatically kick in
whatever Fate or Destiny was achieved.
Celestials and ethereals killed in Poughkeepsie do not suffer the True Death, but their equivalent of souls are so locked to their vessels that they cannot win free of them under these circumstances. Their corpses must either be brought out or completely destroyed: if the latter occurs, the entity will be expelled from the Bubble at high speed.Poughkeepsie's unique potential for imprisoning celestials has occurred to more than one Superior; whether anybody has acted on it... well, there's no doubt that somebody has.
Destiny/Fate: both still work in Poughkeepsie, and one can achieve either from inside the Bubble, but neither reward nor punishment will apply until the mortal leaves. The reasons for this are not understood, but are widely considered to be significant.
Disturbance: No disturbance can be generated from inside the
Bubble, and no disturbance from outside of it can be heard, either.
Essence Gathering and use: no Rites work in Poughkeepsie (including daily accumulation). Any
action that would normally gather Essence has no effect, even when the
celestial leaves the Bubble. Essence may
be expended in Poughkeepsie, but to
no effect whatsoever; any Essence spent immediately vanishes without
However, it should be made clear: Essence can exist in Poughkeepsie, and Jean has stated for the record that even an area like the Bubble should not be able to destroy it.
Resonance use: not possible, under any circumstances (including remote viewing). This includes the Shedite / Kyriotate resonance; taking a possessed individual into the Bubble breaks the possession. This is widely known.