Nightshade

Skath is a disease that befalls Cheshires.

Skath locks Cheshires into the state of having a physical avatar, though they can still morph it at will – excepting the gradual crusting with exo-skeleton-like protrusions, which they cannot shirk. Once fully encrusted with it, they die. (Theoretically, they can always avoid getting fully encrusted by expanding around it, but it just becomes more and more unwieldy as time goes on.)

In an effort to combat Skath, the Cheshires created Chimera to find a cure for them.