Arauthal, the Cindering

Hellfire. Fire damage dealt by Arauthal ignores damage resistance.

Hellfire Embodiment. Any creature that starts their turn within 15 feet of Arauthal take 7 (2d6) points of fire damage.

Ireful Defense (3/Day). When Arauthal fails a saving throw, he can succeed instead. When he does, attack rolls made against him have advantage until the end of his next turn.

Siege Monster. Arauthal deals double damage to objects and structures.

Multiattack. Arauthal can use his Frightful Presence. He then makes three attacks: one with his bite and two with his claws.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 14 (4d6) fire damage, and the target is set on fire for 1 minute or until the target or a creature who can reach them uses an action to extinguish the flames. A creature who is on fire at the start of their turn takes 10 (3d6) fire damage. If a creature who is already on fire is set on fire again on a subsequent turn, the damage isn’t cumulative, but the duration of the fire resets to 1 minute.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 20 (3d6 + 10) slashing damage, and Arauthal can move the target up to 15 feet horizontally.

Frightful Presence. Each creature of Arauthal's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 21 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the Arauthal’s Frightful Presence for the next 24 hours.

Scorching Breath (Recharge 5–6). Arauthal exhales fire in a 150-foot cone. Each creature in that area must make a DC 25 Dexterity saving throw. On a failed save, a creature takes 95 (30d6) fire damage, and any mundane metal objects they are wearing or carrying are melted into slag and destroyed. On a successful save, a creature takes half as much damage and their equipment isn’t destroyed.

Additionally, the fire remains in that area until the end of Arauthal's next turn. For the duration, that area is difficult terrain, and a creature who enters that area for the first time on a turn or ends their turn there takes 14 (4d6) fire damage. This fire is not considered magical.

Blazing Rush. Arauthal sheds his physical form to become a being of hellfire until the end of his next turn. He then moves up to half his speed. If he enters a creature’s space during this move, the creature takes 10 (3d6) fire damage.

Regenerative Flames. If Arauthal is within 10 feet of any non magical fire, Arauthal can extinguish the flames and heals 20 hit points for every 5 feet of fire within range.

Ignite the Insolent. When a creature within 120 feet of Arauthal attacks him, the attacker must make a DC 21 Dexterity saving throw. On a failed save, the attacker is set on fire for 1 minute or until the attacker or a creature who can reach them uses an action to extinguish the flames. A creature who is on fire at the start of their turn takes 10 (3d6) fire damage. If a creature who is already on fire is set on fire again on a subsequent turn, the damage isn’t cumulative, but the duration of the fire resets to 1 minute.

Villain Actions

Arauthal as three villain actions. He can take each action once during an encounter after an enemy’s turn. He can take these actions in any order but can use only one per round.

Action 1: Cinderfall. A 30-foot-radius cloud of smoke and cinders surrounds Arauthal until the end of his next turn. That area is heavily obscured for creatures other than Arauthal. An enemy who needs to breathe and starts their turn within the cloud must succeed on a DC 21 Constitution saving throw or be poisoned for 1 minute (save ends at end of turn).

Action 2: Ashen Armor. Arauthal's skin hardens into a protective armor of ashen scales, granting him 100 temporary hit points. Until all these temporary hit points are gone, a creature within 5 feet of Arauthal who touches him or hits him with an attack takes 14 (4d6) fire damage.

Action 3: Supernova. Arauthal unleashes a massive burst of light and heat. Each creature within 120 feet of him must make a DC 21 Constitution saving throw. On a failed save, a creature takes 35 (10d6) fire damage plus 35 (10d6) radiant damage and is blinded. On a successful save, a creature takes half as much damage and isn’t blinded. The blindness lasts until cured by a power, a spell, or a similar supernatural effect that removes the blinded condition.