Carnifax of Chaos (Boss Fight)(CARN)

Actor. While being ridden by the Wicked Usurper, Carnifax has advantage on Charisma (Performance) checks.

Animatronic Fortitude. When Carnifax would be reduced to 0 hit points, he can make a Constitution saving throw, falling to 1 hit point instead on a successful save. The DC is 10, or half the damage he incurred (rounded down), whichever is higher. If the damage is incurred from a critical hit or melee attack, he automatically fails his saving throw.

Instability. When Carnifax dies, he explodes, dealing 14 (4d6) lightning damage to all creatures within 20 feet of him.

Keep Distance. As a bonus action, Carnifax takes the Disengage action. After doing so, at any point during this turn, if the Wicked Usurper has dismounted and Carnifax is within 5 feet of the Wicked Usurper, he can force the Wicked Usurper to mount him again without requiring movement expenditure.

Mounted Combat Quick Rules:

• The Wicked Usurper must spend 15 feet of movement to mount Carnifax.
• Opportunity attacks may target either Carnifax or the Wicked Usurper.
• If Carnifax is moved against his will, or if the Wicked Usurper is knocked prone, the Wicked Usurper dismounts on a failed DC 10 Dexterity saving throw. He doesn’t fall down, however, due to his hover speed.
• If Carnifax is knocked prone, the Wicked Usurper automatically dismounts.

Multiattack. Carnifax makes a bite attack, then uses his Steam Breath, if available.

Bite. Melee Weapon Attack: +9  to hit, reach 10 ft., one target. Hit: 23 (4d8 + 5) piercing damage.

Steam Breath (Recharge 5-6). Carnifax exhales scalding steam in a 60-foot cone. Each creature in that area must make a DC 17 Constitution saving throw, taking 35 (10d6) fire damage on a failed save, or half as much on a successful one.

Boss Actions
When either Carnifax of Chaos or the Wicked Usurper fail a saving throw, they can choose to succeed instead. If they do so, they both lose access to one boss action of their choice. All boss actions are restored when either finishes a long rest.
On initiative count 20 of each round (losing initiative ties), they can together activate all of the following boss actions.

Recharge Steam Breath. Carnifax has a steam-powered engine on his neck, which falls off if he loses this boss action. When used, Carnifax recharges one use of his Steam Breath.

Cast a Spell. The Wicked Usurper drops his staff if he loses this action. When used, he casts a spell with a casting time of one action.

Roll Call. If this boss action is lost, the flags atop the towers burn away. When used, the flags signal a new scene, and every creature in Kings and Chronicles, including the Wicked Usurper and Carnifax of Chaos, must succeed on a DC 10 Charisma (Performance) check or take 35 (10d6) psychic damage.