Stat block in English

Nightmare
2014Large fiend, Neutral Evil
STR
18
DEX
15
CON
16
INT
10
WIS
13
CHA
15
Senses passive Perception 11
Languages understands Abyssal, Common, and Infernal but can't speak
Challenge 3 (700 XP)
Source Monster Manual
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: , reach 5 ft., one target. bludgeoning damage plus 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.