Nightmare, Variant (5e Creature)
From D&D Wiki
Medium construct, chaotic evil
Saving Throws Charisma, Strength
Blindsight. This creature has blindsight for 200 feet. Beyond this radius, the nightmare is blind.
Shapeshifter. The nightmare targets a single creature, not created. This creature must make a Wisdom saving throw equal to DC of 16. If the creature fails, the nightmare breaks into the creature's mind and shapeshifts into the creature's worst fear. In this form, the creature must make another Wisdom saving throw with the same DC of be frightened of the nightmare for as long as the nightmare is alive or conscious.
Sunlight Sensitivity. While in sunlight, the nightmare has disadvantage on attack rolls, as well as Wisdom checks that rely on sight. After about a minute in direct sunlight, the nightmare takes 1d4 radiant damage for every turn it spends in direct sunlight.
Telepath. The nightmare can communicate feelings and images through telepathy, but no words as it doesn't speak
Claws. Melee attack: +9 to hit, reach 5 ft., one target. Hit: 8 (2d8) slashing damage.
Nightmares are fearsome beasts that love to strike fear in the hearts of any creature it comes up to, especially in wandering adventurers who wander into their masters' homes. Its true form is much like that of a shadow's, but with huge claws that drag across the ground and longer legs. They have no eyes, but they have a mouth filled with never-ending rows of teeth. They never leave footprints because their never truly there, only there in the mind of an enemy. They are mostly used to test an adventurer's courage, to find out if they can conquer their worst fears. They are mostly created by the dark lords of Shadowfell or the Hells to scare wandering creatures from something they want to hide.