Fan Casting Proteus the Power-Mad in Ghostbusters: Multiverse Mayhem

Origin- In Medieval Era, Proteus, the priest to the British king, discovered that there are worlds connected to this world, he believes that by bringing every world with the proper magic, every universe, and this universe would become one. So after learning dark magic, he sold his body and soul to the dark beings from the dark realm for the power to open the gateway to and from every dimensional world. But, the king ordered the monks to captured the dark spirit of Proteus, and imprisoned him inside the dark reliquary gift from the dark being, locked up the reliquary inside a chest, and sank the chest somewhere at the bottom of the Atlantic Ocean to ensure that Proteus would never be found.