Doppelganger

 Saw a doppelganger transform the other day... Blimey, was that an unpleasant thing to witness. Heard its bones crack and saw its skin tear... Turned from a cow right into a strong broad shouldered man.  

-Guardsman of Greyrock, Ellewall

Doppelgangers are a formless species, though if they remain formless for over 24 hours they will die. A doppelganger can switch between many forms, most often animals. Each doppelganger is good at certain things. Some will be great at turning into cats, others into birds and others even into humans. A doppelganger can live up to ten years.

Some people consider doppelgangers sentient, but scholars have discovered that they recieve the intelligence of whatever form they assume. This means they can be as stupid as a goat, or as smart as a man. Doppelgangers can be exposed by throwing water with Brightflower mixed in it on them, or by ( if they have assumed a human form ) asking them a question that only the true individual would know.

Doppelgangers have become a rare phenomenon.