Thank you for the question for Biblical metaphor for the devil, “What is a metaphor for the devil in the Bible?”
As I am thinking through in my mind about the descriptions of the devil, there is only one metaphor that I can think of and that is possible the usage of the serpent. Even in the Genesis 3 account of the serpent appearing to Eve, it may be that the Satan enter a serpent and spoke through it and not necessarily a metaphor.
Here are common references or names of Lucifer, the fallen angel:
A. The Serpent or the Ancient Serpent: (Gen. 3:1, Rev. 20:2)
B. The Red Dragon (Rev. 12:9)
C. Satan (Rev. 12:9)
D. The Devil (Rev. 12:9)
E. The Accuser of the Brothers (Job 1:9–11, Rev. 12:10)
F. The Prince of this world (John 12:31)
G. The ruler and Prince of this air (Eph. 2:2)
H. Lucifer, Morning Star (Isa. 14:12)
I. Son of the Dawn (Isa. 14:12)
J. Belial (II Cor. 6:14)
Base on the above references or names of the first fallen angel, the references are not metaphors but descriptions of Lucifer of his beauty or his role in this world. Possible metaphors or similes is an angel of light (II Cor. 11:14 ) or Morning Star (Isa. 14:12) but his appearance may have been bright as a “star”. The Scripture indicates that he may have been one of the most highly created creatures of God, chief among the angels.
SUMMARY: I may be wrong but I think that the names or descriptions of The first fallen angel are not metaphors but reflection of his character and function.
For more perspetives:
https://www.quora.com/What-is-a-metaphor-for-the-devil-in-the-Bible