Everything

Assuming that you have a creature who’s capable of complex social interaction, the impersonation process involves a lot of subtle cues. Again, dropping a cloned sheep into a herd is fairly simple… though the other sheep will probably regard the stranger as a little odd. A memorable individual, however, is much harder to impersonate correctly; she might look just like the individual in question, but folks can usually tell an imposter from the real deal unless the impersonator limits her interactions or has serious skills and the data to back them up.

In game-terms, assume that an impersonating creature (clone, shapeshifter, disguise expert, etc.) uses the Subterfuge Ability + either Intelligence or Wits in order to pass for the imitated character; simple acts of deception have a difficulty of 5 or 6, but challenging acts of deception require higher difficulties.

Beyond that, the imposter adds +1 to simple social interactions, +2 to complex social interactions, and +3 to intimate social interactions until and unless she’s had time to adjust her impersonation to the situation. Simple interactions involve basic surface-level behavior (greeting, eating, small-talk, and so forth); complex interactions involve dealing with people the original person knew fairly well (co-workers, casual friends, etc.); and intimate interactions involve dealing with the people that the original knew well (relatives, close friends, lovers, etc.). Success means that the imposter has managed to keep the charade going, failure means that she’s made some minor mistake, and a botch signifies a revealing error that threatens the whole masquerade. Thus, it’s easy to use Life magick as a minor disguise technique, but difficult to maintain a sophisticated impersonation for long… especially among the folks who knew the original pretty well.