Metamorphosis technique

The metamorphosis technique was a Rutan technology enabling the amorphous Rutans to mimic the shape of specific individuals and impersonate them as a tactic in their war with the Sontarans. (PROSE: Blind Terror)

Although Rutans were able to change their shape in the 1100s, (AUDIO: Castle of Fear) the Rutan scout referred to the "new" metamorphosis technique at the start of the 20th century. When the Fourth Doctor faced it on Fang Rock, the scout was highly trained in the new technique, impersonating key members of the lighthouse staff. (TV: Horror of Fang Rock)