Metamorphosis

Seán Manchester (from his writings) on vampire metamorphosis:

It is not correct, in my experience, to understand that the corporeal form"never leaves its resting place," though I am familiar with the theory that it can remain in an undead state as a sort of substitute for the demonic agency, which materialises on its own, retaining the physical likeness of the human corpse with the possibility of assuming other likenesses as well. 

The corporeal form, through its demonic agency, does have the supernatural ability to dematerialise and rematerialise outside the confines of its tomb. This is extended to all manner of metamorphosis, as described in my published works. So it can assume other likenesses, and retain more than just the spectral appearance of an apparition when it returns to the corporeal from something else.

Due to the words I uttered, Lusia took the form of what I at first thought to be "a misty vapour stealing towards me." The exorcism continued for almost an hour before "an uncanny change" in my environment occurred that led to "the outline of a figure on the grave before me." Whether or not it was metamorphosing into what I was about to behold, the next manifestation was indeed a diabolical abomination "the size of a large cat" which "scurried back and forth in the most terrifying manner around the perimeter" of salt interspersed with cups of holy water. This form was impaled as the exorcism reached its climax. It straight away began to metamorphosise back to its original corporeal state, albeit now God's true dead, requiring re-internment and the prayers for the dead. The formula I used is found in the pre-Vatican II Rituali Romano.