Oneirovore

Oneirovore
The ancestors of these Fiends were servants of the divine and Fey which devoured the nightmares of mortals, bringing restful sleep. Imported into the Nine Hells and cultivated by devils, dream eaters, as they're also known, became a powerful weapon in subtly corrupting mortal minds. They can be found grazing wherever the toxic foliage of the Nine Hells grows, often guarded by low-status devils and hell hounds. When brought to weak points between the planes, their spirits seep into the mortal world. There they browse the dreaming minds of mortals. Often, they devour the hope and wonder that might inspire people to improve their lives.
Placid Herds
Despite their fearsome-looking appearance, dream eaters are oddly passive for a denizen of the Nine Hells. When attacked, their first instinct is to lumber away at their sluggish pace, sending out high, mournful cries that attract every devil and infernal monster within earshot. Their angry herdsmen usually arrive in short order to see off the threat.
Storehouses of Phantasms
Forced to fight, dream eaters' most potent defense is a release of their stored phantasmagoria. This can affect attackers in several ways. A release of nightmares taints the way that non-devils view the world around them, transforming everything—including allies—into hideous sources of fear and threat, whilst the dream eaters themselves fade into the infernal landscape. On the other hand, a release of hope and wonder leaves mortal attackers in a dazed and euphoric state, suddenly taken by wild fancies to accomplish impossible and reckless feats that see them charging off across the hellish landscape, the fight forgotten. The same expulsion of positive dream imagery has a powerful caustic effect against infernal creatures, affecting devils much as a skunk's blast against regular predators.