Gardner Fox returns to script Spectre 6 (Sept/Oct 68), with Jerry Grandenetti and Murphy Anderson on the art.
Fox's story is pretty basic. The Spectre has to deal with an evil ghostly pilgrims who seal off the oldest part of Gateway City.
The pilgrims invoke a demonic entity, Nawor. But what should be apparent, from the clips I have posted, is how exceptional the art is. So incredibly detailed, it really needs to be seen full size, to appreciate it.
The Spectre determines that the pilgrims had tried to invoke Nawor a couple hundred years earlier. The demon allows them to return every century to try again, and this time it worked. Well, briefly.
The only disappointing element to the story is how easily the Spectre ultimately defeats Nawor, by using a Rowan tree. The one name is the other spelled backwards, and the Spectre reasons that is the vital clue to the demon's defeat. But geez it all looks amazing.