Innate Spellcasting. Violet Skull's Innate Spellcasting ability is Wisdom (Spell Save DC 18). He can innately cast the following spells, requiring no material components:

At Will: Control Flames, Fire Bolt, Produce Flame
3/Day: Burning Hands, Hellish Rebuke, Aganazzar's Scorcher, Continual Flame, Flame Blade, Flaming Sphere, Heat Metal, Scorching Ray, Fireball, Dragon's Breath
2/Day: Conjure Minor Elementals, Delayed Blast Fireball, Fire Shield, Wall of Fire, Conjure Elemental, Flame Strike, Immolation, Investiture of Flame
1/Day: Fire Storm, Meteor Swarm

Death Burst. When Violet Skull dies, he explodes in a burst of violet flames. Each creature within 10 ft. of him must make a DC 18 Dexterity saving throw, taking 13 (3d8) fire damage on a failed save, or half as much on a successful one. Flammable objects that aren't being worn or carried in that area are ignited.

Heated Body. A creature that touches Violet Skull or hits him with a melee attack while within 5 ft. of him takes 13 (3d8) fire damage.

Illumination. Violet Skull sheds bright light in a 10-foot radius and dim light for an additional 10 ft.

Magic Resistance. Violet Skull had advantage on saving throws against spells and other magical effects.

Fire Breath (Recharge 5-6). Violet Skull exhales fire in a 60 ft. cone. Each creature in that cone must make a DC 18 Dexterity saving throw, taking 40 (10d8) fire damage on a failed save, or half as much on a successful one.