Mono-morphia
From Tardis Wiki, the free Doctor Who reference
Mono-Morphia is a disease that affects the Whifferdill's ability to change shape. It prevents any shape changing until the disease wear off, therefore it leaves the victim in their form during the point they gain the disease. It seems random to how the disease is gained and the point where it wears off. Frobisher was affected by Mono-Morphia and was stuck in the form of a Penguin. (DWM: Genesis!) The disease wore off before returning to reaffect his abilities. (DWM: Changes/Profits of Doom)
