Plane of Shadow Curse/Transformation

[Elric VIII]

In various books regarding the D&D cosmology, it is often mentioned that creatures that spend an extended amount of time on the Plane of Shadow are altered to match their environment.

Does anyone know of some disease/curse/template that reflects a negative aspect of this (as opposed to the Umbral/Shadow templates)?

I'm looking for something that is not easily removed (possibly driving the PCs to seek aid from an NPC) and has a detrimental effect that encourages immediate removal. I know I can homebrew something, but I usually like to use what is already printed, when possible.

Thanks.

[The Mentalist]

Nothing printed by WOTC or any of the 3rd party books I've read.

[Tokuhara]

In various books regarding the D&D cosmology, it is often mentioned that creatures that spend an extended amount of time on the Plane of Shadow are altered to match their environment.

Does anyone know of some disease/curse/template that reflects a negative aspect of this (as opposed to the Umbral/Shadow templates)?

I'm looking for something that is not easily removed (possibly driving the PCs to seek aid from an NPC) and has a detrimental effect that encourages immediate removal. I know I can homebrew something, but I usually like to use what is already printed, when possible.

Thanks.

My 2c:

Short time (about a month or so)- Dark (ToM): It's essentially a watered down Umbral template.

Medium time (<a year)- Umbral: Treat it like an advancement of a disease

Long Time (>a year)- Shadow: Worst case of Shadow Plane Sickness

[Alleran]

The Dark template can be gained in the Cormyr - Tearing of the Weave adventure, by going through a Shadow Gate too often. So that's a possibility, but it's not really a negative effect per se.