NPC “The Baron”.
A spirit. Appears as a tall man wearing cheaply made facsimile of elaborate and formal clothes. Likes to drink rum, tell dirty jokes, make passes at the ladies and generally party.

He was the mentor of the necromancer, who the necromancer killed to gain power. He was a very powerful sorcerer, but viewed himself as a protector of the spirits of the dead. He wants the necromancer defeated so that the spirits of the dead can enter the afterlife.

He will help the party on a strictly transactional basis. They have to pay him his price before he will help. He may be willing to accept the promise of future payments, but any failure to pay in full will make him an unrelenting enemy.

He has the power to send other spirits to help the party, these spirits will possess the body of the party member and they will gain the memories of that spirit permanently, as well as the powers/skills/abilities that spirit had while it was alive during the possession. The possession is of a random duration and the PC will simply be a passenger in their own body while the possessing spirit is in control.