Everything

Daemonic Possession lets a vampire insert a soul into a freshly dead body. This does not turn the reanimated corpse into anything other than a reanimated corpse, one that will irrevocably decay after a week, but it does

give either a wraith or a free-floating soul (say, that of a vampire using Psychic Projection) a temporary home in the physical world.

System: The body in question must be no more than 30 minutes dead, and the new tenant must agree to inhabit it — a ghost or astral form cannot be forced into a new shell. However, most ghosts would gladly seize the opportunity. Should the vampire, for whatever reason, wish to insert a soul into another vampire’s corpse (before it crumbles to ash), the necromancer must achieve five successes on a resisted Willpower roll against the original owner of the body. Otherwise, the interloper is denied entrance.

Note: The soul can use whatever physical abilities (Athletics, Brawl, Potence) his new fleshy home possesses, and whatever mental abilities (Computer, Law, Presence) he already possessed. He cannot use the physical abilities of his old form, or the mental abilities of his new one.