"The rainbow dragons are creatures of legends and myths. To be fair, in search of rare creatures I've been to all the worlds, but I have never seen a Rainbow Dragon. I believe that if they ever existed, they are long extinct. More likely they have always been a product of the rich imaginations of the ancients."
(from the travel notes of "Wild Monsters" by famous researcher Sir Atten Vidborough)
Elite flying fighter
Note: This is a Main quest reward.