"The Gods of Pegāna: Kabok the Prophet" by Lord Dunsany

The picture used is "Sermon and Deeds of the Antichrist" (1501) by Luca Signorelli. Note in particular in the front just right of center, the devil whispering to the antichrist. As Kabok claims Mung whispers to him. But, Kabok is just another false prophet, like the Antichrist is sometimes said to be.

The follow along: https://gutenberg.org/cache/epub/8395/pg8395-images.html#KABOK_THE_PROPHET