Lifespan: unknown
Diet: unknown
Average height: unknown
Average weight: unknown
Average length: unknown
Geographic distribution: unknown
Frequency: common
A spirit form is in essence the magic of a soul, part of the link to Fronima. They are very rare however. This is because spirit forms are the result of a mage dividing themselves from their magic, which is generally not a desirable occurrence, as the mage then completely forfeits the use of powerful spells. Oftentimes, this occurs as the result of trauma, no matter the age.
Once separate, a mage cannot reunite themselves with their magic, so to use massive spells once more, they must be capable of calling their spirit form, something very difficult to do, considering they no longer are connected as completely as before. Without their spirit form present, they cannot conduct major magic. (For small slight of hand tricks, a spirit form is not required, as all pendragons have a link to Fronima all their lives. Dividing oneself from magic only separates them from the majority of the link, never all.)
The spirit form can take any form they choose, but they stay in that one form. For instance, if a sorcerer's spirit form is a prey-bird, it remains a prey-bird. Spirit forms can carry on conversation and are of no substance, so they can pass through walls and such. They usually share the same temperament as their caller, whoever they belong to. Gender is not an issue, they can be either, without considering the gender of the pendragon which "owns" a particular spirit form.
Most pendragons cannot see them, only those who have divided themselves and "reunited", or those of incredible mental skill, can. Oftentimes they are not even noticed by the 'dragon in question, because the existence of such things are so rare that one is not taught about them, nor looks out for them, in the first place. Those to whom the caller is close to or who they want to be able to see the spirit form can also see it, but no one else. (There must be a connection between two pendragons, to be able to see the embodiment of one's magic. Without a connection, you cannot hope to see it.)
Because spirit forms are a pendragons' magical link to Fronima, every mage does have one. A spirit form does not become an entity to converse with on their own until separated in some way from the mage, because until that point, a spirit form resides inside oneself. Those who have not divided and then reunited themselves, as with religious leaders, or who have an equally high mental prowess, can project their magical selves to speak with the gods.