Nightmare

Large fiend, neutral evil

Armor Class 13 (natural armour)

Hit Points 68 ([roll:8d10+24})

Speed 60ft Fly: 90ft

STR

18 +4

DEX

15 +2

CON

16 +3

INT

10 0

WIS

13 +1

CHA

15 +2

Damage Immunities fire

Senses passive Perception 11

Languages understands Abyssal, Common, and Infernal but can't speak

Challenge 3

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.

Actions

Hooves. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 ( 2d8+4 ) bludgeoning damage plus 7 ( 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.