I don't have a copy of Street Magic in front of me, but I believe I described the effect in the section about the Deep Metaplanes. It basically limits the amount of time you can spend in the Deep Metaplanes before your astral form falls apart.

Returning back to your home plane (or even a normal metaplane) will end the effect, since metahuman astral forms can sustain themselves just fine in those parts of astral space.

God damnit I wish they had gone with a different namje, I told them this would happen. That word isn't even otherwise in the vocabularly f most English speakers. Technically it means the bubbly quality of champagne, but the only reason you'd ever decide to use that word is if you were ESL and thumbing through a thesarus. I lobied for "Instability" but no. Fuckers.

Anyway...

As written, nothing.

Magicians who go to the deep metaplanes lose 1 Magic temporarily for every hour they spend there. Your magic returns at the rate of 1 per hour you spend back on Earth, and if it drops to zero you are dumped back into your body (presumably you are disrupted, but it doesn't actually say that. (p. 130) Thisis described as being "like" Evanescence, but it isn't actually Evanescence, it's just something that happens.

The Evanescence (shudder), power doesn't do anything to you unless you're a spirit, and it doesn't do anything to you once you've inhabited a body. Presumably that means begun inhabitting a body, because otherwise every spirit would lose double its Force (and thus die) while trying to inhabit a body. Furthermore, True Form Spirits are exempt from Evanescence even though it doesn't say they are.

That section is a mess, and even though it's not my fault, I apologize anyway.

-Frank