Ash Beast

Volcanic. This creature is shrouded in a fog of volcanic ash. Everything within 15 feet of this creature is considered heavily obscured. A creature in this area must make a Constitution saving throw at the end of their turn. The DC is equal to 9 + the number of times the creature has entered or began their turn in the fog. On a failure, the creature gains a level of exhaustion as they choke on this ash. A creature that does not need to breathe, or has an alternate source of air, is immune to this effect. A creature that covers their mouth has advantage on this saving throw.

Quenched. Dousing this creature with a large amount of water ends its Volcanic effect for 1d4 rounds, but any other creatures within the cloud when this occurs take 14 (4d6) poison damage, halved on a Constitution Saving throw, as volcanic gasses are washed off this creature's body. For this time, any fire damage this creature deals is halved.

Heated Body. Any creature that touches the Ash Beast or makes a melee weapon attack against it takes 4 (1d8) fire damage.

Innate Spellcasting. The Ash beast's spellcasting ability is Constitution (spell save DC 16, +8 to hit with spell attacks). The Ash beast has following spells prepared:
At will: Fire Bolt 
3/Day: Flaming Sphere, Faerie Fire,
1/Day: Wall of Fire, Fireball, 

Multiattack. The Ash Beast makes one attack with its claws, and shoots one firebolt from its mouth.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 10 (2d6 + 3) bludgeoning damage. 

Firebolt. Ranged Spell Attack: +8 to hit, range 120 ft., 1 target. Hit: 11 (2d10) fire damage.

Smoke Blast (1/day). All creatures within 100 feet must make a DC 15 Constitution Saving Throw. On a failure, they take 10 (3d6) fire damage, 10 (3d6) poison damage, and are blinded and incapacitated for 1 round as smoke and dust fill their eyes and mouth. Creatures take half damage and are not incapacitated on a successful save.