As the sun set over the mudflats, the village was mostly quiet. It had been a busy day, and the hard working folks were shucking off mud caked boots and overalls and sitting down for a well deserved hot bite of supper and a cool glass of something with a little bite. The sky was awash in pastels ranging from pink and orange in the west over the water, to blue and violet in the east. The mud shimmered in the dying light.
Up in the village, two old men sit on the porch of a wooden cottage overlooking the mudflats. The short thin one, with dark skin like worn old leather squints out toward the sun.
"You'll ruin your eyes doing that." His larger but no less worn companion warns, as he tugs his soft brimmed hat lower on his head to block the sun.
"What do I have to save them for anyway?"
"Well, there's always checking out the cute things coming back from the mud."
"Like them?" the smaller one points. Down below, a line of robed figures sets out into the mud, making their way slowly away from the shore.
"Crazy cultists aren't exactly what I was talking about..."
"What are they doing?"
"They think they're aliens."
"No, the cultists think the oysters are aliens. They're out there to get... I don't know... oyster inspiration or somesuch."
"Well if that ain't the looniest thing I ain't ever heard. And I've been stuck around you all my life, so I've heard some pretty damn loony things before."
So, these guys got a little too into heavy metals (lead mostly) and they're off their collective rocker. They don't fear the reaper or the black blade, and they're no agents of fortune or anything else mystical.
They do however, have one magic item among them, a cursed mirror. In its reflection the viewer sees that which is patently untrue (oysters are aliens for example) and yet they will believe it with a fanatic's fervor. Whether that fervor is violent or not all depends on the group. If viewed by multiple people, they will all see the same untruth. Every time it is viewed by a new person (as long as no one at the time has looked into the mirror before) will see the same untruth as anyone else who has before viewed it.