Actions

Multiattack. The cauchemar makes one Bite attack and one Hooves attack. Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) piercing damage plus 7 (2d6) poison damage. Hooves. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage plus 7 (2d6) acid damage.   Acid Breath (recharge 5-6). The cauchemar exhales a 15-foot cone of acid droplets. Each creature in that area must make a DC 15 Constitution saving throw. On a failure, a creature takes 21 (6d6) acid damage and is poisoned for 1 minute. On a success, a creature takes half the damage and isn’t poisoned. A poisoned creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.   Ethereal Stride. The cauchemar and up to three willing creatures within 5 feet of it magically enter the Ethereal Plane from the Material Plane, or vice versa.

Regional Effects

Where the cauchemar passes its hoofprints sprout small green and black plants that look native to the local flora but brushing them will incur 1d4 poison OR 1d4 acid damage randomly determined.   Any heavy brambles within 100 feet become difficult terrain for anyone other than cauchemar and its rider. The brambles are treated as the spell Wall of thorns    

Suggested Environments

The Cauchemar de la Forêt can be found in dense forests, lush jungles and the deepest swamps when their servitude to their dragon Masters. The only way they are freed is through the dragons death, then they go to great lengths finding someone worthy of their Master's cunning to serve.