Astralomitis

Astralomitis was a disease that affected astral dragons.

Considered rare and unusual, astralomitis inhibited an astral dragon's ability to travel the planes via plane shift and it was more common amongst astral dragons who switched between planes frequently. If an astral dragon was on a plane other than the Astral Plane when struck by this disease, it was unable to return, and there was a chance that insanity would ensue. It lost the ability to cast any spells in this state and ferociously attacked any creatures nearby, with its madness lending it greater force, while its breath weapon functioned as normal. This state could last for two to five days, and resulted in the death of the dragon, with it collapsing and dying in less than four hours.

If it could somehow return to the Astral Plane before this time (such as via a portal or another's aid), the sickness and insanity slowly diminished, but it was left unable to switch planes. The disease had no known cure except for a wish spell.