Blood & Bone Devil

Lord of Flesh and Bone. The Devil can alter their physical form and voice in any way they please.

Blood-Enhanced Blades. The Devil’s attacks are magical for the purpose of overcoming resistances.

Rapid Muscle Growth. The Devil has advantage on strength checks and saving throws on contested checks as well as checks and saves to avoid or escape being grapple/restrained.

Legendary Resistance (2/day). If the Devil fails a saving throw, it can choose to succeed on it instead.

Laser Focus. The Devil has advantage on concentration checks. 

Spellcasting. The Blood & Bone Demon is a 12th-level spellcaster. Its spellcasting ability is charisma (spell save DC 18, +10 to hit with spell attacks). The Blood & Bone Demon has following Sorcerer spells prepared: 

Unlimited: [Hellish Rebuke (3rd level)]

1/day: [Wall of Fire], [Immolation], [Melf’s Minute Meteors]

2/day: [Fireball]

Multiattack. The Devil can attack three times with their Boneclaw Slash attacks. Only one attack can be replaced by a spell. Two attacks can be replaced with a Boneclaw Hellsweep attack.

Boneclaw Slash. Melee Attack: +11 to hit, reach 15 ft., 1 target. Hit: 22 (5d6+7) slashing damage.

Boneclaw Hellsweep (Recharge 5-6). The Devil ignites its blood-soaked boneclaws and sweeps them across a 15 foot cone. All creatures within that area must make a Dexterity saving throw DC 19 or take 22 (5d6+7) slashing damage and 20 (10d4) fire damage.

Rib Gnashers (Recharge 5-6). The Demon can grow its ribcage into a set of gnashing fangs and attempt to pierce a creature within 10 feet of the Demon. The targeted creature must make a Dexterity or Strength saving throw (Creature’s choice) DC 19 or take 24 (6d8) piercing damage and be grappled on a failed save, or take no damage and avoid being grappled on a successful save. The creature can repeat the save on each of its turns and will be freed if they make a successful save. The Demon can not use this attack while grappling a creature, and can end the grapple with one of its bonus actions.

When a bonus action is used, it is unavailable to use again until the Rib Gnashers skill is recharged.

Toss. The Devil tosses a grappled creature away to an open space within 20 feet. The thrown creature will be knocked prone.

Hellstorm Breath. A mouth grows on the Devil’s stomach and unleashes a blast of fire. All creatures in a 30 foot cone must make a Dexterity saving throw DC 19 or take 40 (10d8) fire damage on a failed save or half as much on a successful one. A creature grappled by the Devil automatically fails this save. The grappled creature will be let go after taking the damage and will be left prone.

The Devil has 2 legendary actions per round. It can only use them after the end of another creature’s turn. It regains expended actions at the start of each of its turns.

Boneclaw Slash (1 action). The Devil makes one Boneclaw Slash attack.

Leap (1 action). The Devil leaps to an unoccupied space within 30 feet.