Nightmare

Illumination. The nightmare sheds bright light in a 10-foot radius and dim light for an additional 10 feet.

Riding Flames. Any creature riding a willing nightmare is resistant to fire damage. A creature riding the nightmare without the nightmare's permission takes 3 (1d6) fire damage at the start of each of the nightmare's turns.

Multiattack. The nightmare makes two Flaming Hoof attacks.

Flaming Hoof. _Melee Weapon Attack:_ +6 to hit, reach 5 ft., one target. _Hit:_ 7 (1d6+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.

Burning Hoofprints. The nightmare increases the intensity of the heat on its hooves. Until the start of its next turn, it leaves burning hoofprints in any surface through which it walks, creating a trail of fire in its wake. A creature that enters a space with burning hoofprints for the first time on a turn or starts its turn there must succeed on a DC 13 DEX save or take 3 (1d6) fire damage. The hoofprints stop burning at the start of the nightmare's next turn.