Gamigan

The fourth spirit named among the demons of the Goetia.  According to Scot's Discoverie of Witchcraft, Gamigan is a great marquis ruling over thirty spirits.  He first manifests in the form of a little horse, but he can change this shape to assume the form of a man.  Gamigan is a great marquis ruling over thirty legions of lesser spirits.   Gamigan's main power is a form of necromancy.  He is reputed to be able to call upon the souls of those drowned in the sea as well as any souls confined to purgatory and cause them to appear in "airy" or non-physical bodies.  He can further force them to submit to interrogation, answering any question put to them.  His name is given as Gamygyn by Wierus in his Pseudomonarchia Daemonum.  In the Goetia of Dr. Rudd, this demon's initial form is said to be that of both a little horse and an ass.  He is constrained by the angel Elemiah.  In the Book of Incantations, he is also a marquis who appears in the form of a little horse or donkey.  He teaches liberal sciences and gives an account of the souls who die in sin.  See also BOOK OF INCANTATIONS, GOETIA, RUDD, SCOT, WIERUS.
THE DICTIONARY OF DEMONS, REVISED AND EXPANDED, M. BELANGER (2021)

Samigina or Gamigm is a spirit of external necromancy.  He allows communication with the shades of the dead, specifically on dreaming levels.  One may also witness 'faces' in a black mirror while communicating with him.  It may be recommended that the magician utilizes EVP to record Samigina or other shades in the place of invocation/evocation as well as within a graveyard.  Goetic rites may be performed but with less 'tools', it then will rely on the sorverers' ability to go forth into a trance to summon such latent forces.
LUCIFERIAN WITCHCRAFT:  THE GRIMOIRE OF THE SERPENT, MICHAEL W. FORD, THIRD TRADE EDITION (2009)