Large fiend, neutral evil
- Armor Class 13 (Natural Armor)
- Hit Points 68 (8d10+24)
- Speed 60 ft., fly 90 ft.
- Damage Immunities Fire
- Senses passive Perception 11
- Languages Understands Abyssal, Common, And Infernal But Can’t Speak
- Challenge 3 (700 XP)
- Confer Fire Resistance. The nightmare can grant resistance to fire damage to anyone riding it.
- Illumination. The nightmare sheds bright light in a 10-foot radius and dim light for an additional 10 feet.
- Hooves. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: (2d8 + 4) bludgeoning damage plus (2d6)fire damage.
- Ethereal Stride. The nightmare and up to three willing creatures within 5 feet of it magically enter the Ethereal Plane from the Material Plane, or vice versa.