What type of immortality is this?

[ByArrow]

Daren would later explain that the most powerful Old Ones could never be fully killed and that their spirits remained outside of their corporeal bodies, awaiting opportunities to return to physical form

As one of the most powerful Old Ones, Nova could never be completely destroyed, even if her body were to perish, her essence would live on and she could find ways to come back into being

 

[ActuallySpaceMan42]

Depends on how exactly they return to physical form, and come back into being.

 

[Wikisource]

Type 4 or possibility is 6