An ignis fatuus, perhaps; a Jack-o'-lanthorn begotten of putrescence.
To get something for nothing is the "ignis fatuus" ever in the lead.
He had not been imposed upon by his fancy; he had not been deceived by some ignis fatuus.
It is, in truth, a shadow as intangible as our own; an ignis fatuus of our being.
It is only the meteoric light of the ignis fatuus, soon extinguished.