Beastiary : my own version

Spectre

A spectre is a rather disturbing spiritual species of Cambion who can leave their physical bodies and possess the bodies of the deceased using them as hosts.

These half demons are sometimes looked down upon by other supernaturals due to there gothic nature and morbid habits. Despite this judgement they are still fearer by some and are often hired as assassins by other supernaturals because despite there strange methods they are normally successful in there kills.

Spectres don't normally have a shift however when they touch a deceased body they can possess it leaving there own body behind, this will cause the deceased body's veins to illuminate neon blue which glow through the skin, the veins around the arms and neck are normally the most visible, there is also a faint light blue glow that dances behind the pupils, these features normally are more prominent when the body is put under strain.

The body's decay is slowed down but still proves a problem causing a spectre to not able to possess a dead body for an extensive amount of time without have to return back to there own body.

A Spectre can chose to leave their host and return back to their own body anytime they want however has to make physical contact to enter a new one. If their host takes to much physical damage it can't contain the spectre's essence causing the creature to be painfully forced to return back to their own body.

Powers and abilities (Own body):
In there own body they don't have access to the true extent of there power as they are necromatic, so they are empowered by death, this why they are so much stronger while possessing a corpse.

Longevity: Like other Cambions they age slower than humans allowing them to live hundreds, maybe even thousands of years.
Death sense: They can psychically sense the presence or relation of death. Such as being able to sense if a death has occurred in there current location or has occurred around an object they have touched. They can also sense when someone close to them dies even if they are countries away. Spectres can also sense if someone is an undead being such as a Strigoi, Revenant or a Spectre possessed corse simply be being near them.
Necromancy: They can use the magic of the dead, similar to witches, however the full limits of there use of this magic is unknown.
Necromatic possession: As explained above spectres can possess to bodies of the deceased via physical contact.

Powers and abilities (Dead body):
Because of there necromatic nature being the body of the deceased grants them power.

Superhuman strength: They are very strong capable of physically engaging with other strong supernaturals such as werewolves and wendigo, they can bend steal and break bones with there bare hands using little effort.
Superhuman speed: They can be very fast, agile and swift with their movement capable of easily outrunning humans and some other supernaturals.
Superhuman endurance: Due to being in a deceased body they don't tire, hunger or have any need for oxygen so can be drowned or strangled, only thing they don't have enough of is time. They will also feel no pain and can take an excessive amount of physical trauma before the spectre inside is forced to leave.

Weaknesses:
Despite spectres reputation they can still be hurt and killed by something like all supernaturals.

Holy objects: Holy objects such as holy water will hurt but not kill a them, even when in the body of the deceased.
Sacred ground: They can't step on holly ground such as churches, temples or places protected by witches without setting on fire or being stop by an invisible wall.
Physical trauma: They are quite durable in there own body and if there own body dies, even if their essence is in another body, they will truly die.
Undead beings: If a Spectre tries to possess an undead being, such as a Strigoi or a Revenant, their essence will be badly damaged due to the body already possessing an essence of its own. However they can possesses soulless zombies.