DEMONS in the Ars Goetia
The demons' names are taken from the Ars Goetia, which differs in terms of number and ranking from the Pseudomonarchia Daemonum of Johann Weyer. As a result of multiple translations, there are multiple spellings for some of the names. 
 
Phoenix (also Pheynix, Phenex, Phoeniex) is a Great Marquis of Hell and has twenty legions of demons under his command. He teaches all wonderful sciences and is an excellent poet. Phenex hopes to return to Heaven after 1,200 years, but he is deceived in this hope. He is depicted as a phoenix, which sings sweet notes with the voice of a child.