Devil's Sight. Magical darkness doesn't impede the devil's darkvision.
Magic Resistance. The devil has advantage on saving throws against spells and other magical effects.
Multiattack. Bregolian makes two melee attacks: one with its bite and one with its tail. It can use Hurl Flame in place of any melee attack.
Bite. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 3 (1d6) piercing damage.
Tail. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 10 (1d8 + 6) piercing damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 10 (3d6) hit points at the start of each of its turns due to an infernal wound. Each time the devil hits the wounded target with this attack, the damage dealt by the wound increases by 10 (3d6). Any creature can take an action to stanch the wound with a successful DC 12 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.
Hurl Flame. Ranged Spell Attack: +7 to hit, range 150 ft., one target. Hit: 14 (4d6) fire damage. If the target is a flammable object that isn't being worn or carried, it also catches fire.
During combat, Bregolian will bury itself underground and regain 1d4 health as well as launch itself at the closest player using its tail and wings, and if failed a dexterity save, 17, doing 1d10 bludgeoning damage and either 1d20+2 bite damage on a failed dexterity save or 1d20+10 tail damage on a success.
Lair and Lair Actions
Tends to lurk in dark regions, caves and such, but if it can not it will bury itself into the ground so only its stick like horns and the moss growing on the top of its head is visible. Tends to live in sheltered areas, so like clearings in forests, valleys, caves and other areas where it can not easily be spotted.