This Dragon is only released for a limited time during it's associated holiday
When dragons pass on, they leave for the big dragon roost in the sky. Most elect to stay, but the ones who return to the Dragon Isles are reborn as Boo Dragons. These dragons watch over loved ones from their previous lives and, in many cases, play pranks on them too!
Boo Dragons are able to play the best pranks because of their incorporeal nature. Trickster Boo Dragons love to float just ahead of where other Dragons are fly. When the unsuspecting dragons fly through the Boo Dragon, they become dripping wet and chilled to the bone, and they have no idea why!
Despite their love of hijinks, Boo Dragons are actually quite shy and try to remain out of sight of other Dragons. They will only become visible if they think no one else is looking; this causes major problems for scientists trying to study these rare dragons.
By the time Boo Dragon reaches its epic form, they are less careful about remaining unknown to other dragons. Epic Boo Dragons will often fly by dragons they don't like, clanging the bell around their necks. The continued hauntings are so bothersome, it causes some dragons to leave their homes behind and move to other islands.