The come from outside our world, from beyond the limits of the astral sphere, appearing like a madness of protoplasmic flesh, somehow contained within congeries of shimmering, iridescent globes. As each glowing sphere floats through the night air, images of a frothing, primal slime, writhing in the chaos of elsewhere, flicker inside them.
Although these iridescent globes are native to the nethermost outskirts of space and time, they are not actively hostile to humans, as a rule. But their presence bends reality too much for the human mind to fathom, and their parasitic life cycle destroys all life that it comes into contact with — and the only creatures that seem suitable in this plane of existence are the intelligent ones.
If these globes arrive and a settlement does not fight against them, it soon disappears. The people are found slain and stripped of their skin, or gibbering mad. Some people are transformed into degenerate cannibals, wearing the flayed skins of those who were once their neighbours and loved ones. Iridescent colours bleed from their eyes, polluting reality itself. They lose all sense of their humanity, living only to prey upon others, until they, too, are found slain, nothing left of them but an empty skin wearing the skins of others.