Warforged Pegasus

Confer Fire Resistance. The Warforged Nightmare can grant resistance to fire damage to anyone riding it.

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

Fire Absorption. Whenever the Warforged Nightmare is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.

Regeneration. The Warforged Nightmare regains 7 hit points at the start of its turn if it has at least 1 hit point.

Trampling Charge. If the Warforged Nightmare moves at least 20 feet straight toward a creature and then hits it with a hooves attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone. If the target is prone, the horse can make another attack with its hooves against it as a bonus action.

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.

Hellish Discharge. Each creature in a 20-foot-radius sphere centered on the itself must make a Dexterity saving throw(DC 15). A target takes 4d6 fire damage on a failed save, or half as much damage on a successful one. The fire spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.