Phenex

The thirty-seventh demon on the Goetia.  According to Scot's Discovery of Witchcraft, this demon appears in the form of a mystical bird also known as a phoenix.  He speaks in a child's voice but also sings sweetly like a bird.  Upon his first appearance, Phoenix flies and flits around, sweetly singing, but his song is merely a distraction.  Those who wish to constrain or compel this demon are cautioned to ignore his music and instead demand that he put on a human form.  Once this has been done, the demon Phoenix will speak of science and poetry.  He holds the rank of marquis and governs twenty legions of spirits.  According to the Goetia, this demon can be made to compose poetry upon request.  He also appears in the Pseudomonarchia Daemonum compiled by Johannes Wierus.  He is Fenix in the French Livre des esperitiz.  In both the Goetia of Dr. Rudd and the Welsh Book of Incantations, his name is spelled Phenix.  According to Rudd, he is constrained with the name of the angel Aniel.  The name of this demon comes from the Greek legend of the phoenix, a mythic bird that lived for five hundred years.  At the end of this time, it would set itself on fire and be reborn from the ashes.  See also BOOK OF INCANTATIONS, GOETIA, RUDD, SCOTT, WIERUS.
THE DICTIONARY OF DEMONS, REVISED AND EXPANDED, M. BELANGER (2021)

Phenex (also Pheynix) is a great Marquis who appears like a Phoenix bird, who has a voice of a child.  Phenex creates a form of music which is something described as a child's chorus, a very beautiful and entrancing form of song from which the magician must command Phenex to take human shape.  If Willed to by the magician, this spirit will take human form in the Black Mirror.  Phenex is a poet and inspires the magician to write and create tomes and works.  Phenex also wishes to return to the Seventh Throne after 1,200 years as well, and governs 20 Legions of Spirits.  Phenex is a natural spirit, whom inspires a careful pondering of the places of nature and the animals within it.
LUCIFERIAN WITCHCRAFT:  THE GRIMOIRE OF THE SERPENT, MICHAEL W. FORD, THIRD TRADE EDITION (2009)