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. The devil makes two attacks with its chains.
Longsword. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 11 (1d8+ 4) slashing damage and (1d8) fire damage.
Supernova (Recharges after a Short or Long Rest).
Alaror stabs his sword into the ground and forces a DC 16 Dexterity in a 30-foot sphere. If anyone fails they take 6d6 fire damage or half as much on a successful one.
Unnerving Mask. When a creature the devil can see starts its turn within 30 feet of the devil, the devil can create the illusion that it looks like one of the creature's departed loved ones or bitter enemies. If the creature can see the devil, it must succeed on a DC 14 Wisdom saving throw or be frightened until the end of its turn.