The Forty-sixth Spirit is called Bifrons, or Bifröus, or Bifrovs. He is an Earl, and appeareth in the form of a Monster; but after a while, at the Command of the Exorcist, he putteth on the shape of a Man. His Office is to make one knowing in Astrology, Geometry, and other Arts and Sciences. He teacheth the Virtues of Precious Stones and Woods. He changeth Dead Bodies, and putteth them in another place; also he lighteth seeming Candles upon the Graves of the Dead. He hath under his Command 60 Legions of Spirits.

The Goetia

With his special affinity with the dead, the Spirit Bifrons could be considered a distant cousin of Baron Samedi (voodoo god of the dead), and an ideal place in which to invoke him would be a deserted graveyard at the stroke of midnight. Here is a genuine way of making a pact with the Spirit Bifrons to gain riches and secret knowledge of the diabolical arts. This is his Seal which must be worn as a pendant, or else he may not obey you: