In Search of New Gods (GM3), softback adventure / magazine for AD&D 1st ed, by Paul Cockburn.
“A scenario for 4th-7th level adventurers.
You’ve earned quite a reputation as fearless adventurers, the sort who take on anything. But what happens when you come face-to-face with the challenge that bested the greatest adventurer in the whole Kingdom? Can you succeed where Feyr-Panniras failed? Can you find what has turned his friends against the Kingdom? And, more than anything, can you survive against the power of the New Gods?”