Lava Keeper

The lava keeper’s innate spellcasting ability is Wisdom (spell save DC 17). It can innately cast the following spells, requiring no material components:
At will: move earth, stone shape
3/day each: wall of fire, wall of stone
1/day each: conjure elemental (earth or fire elemental only), earthquake, fire storm

Each creature that starts its turn within 5 feet of the lava keeper must make a DC 19 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.

The crater between the lava keeper's shoulders erupts in a plume of fire, rock, and toxic smoke. Each creature within 60 feet of the lava keeper must make a DC 19 Constitution saving throw. On a failure, a creature takes 21 (6d6) bludgeoning damage and 21 (6d6) fire damage and becomes poisoned for 1 minute. On a success, a creature takes half the damage and isn't poisoned. A poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The eruption surrounds the lava keeper in a 20-foot-radius sphere of smoke, considered heavily obscured until the end of its next turn. A wind of moderate or greater speed (at least 10 miles per hour) disperses the smoke.

Ranged Weapon Attack: +13 to hit, range 60/240 ft., one target. Hit: 21 (6d6) fire damage, and the target must succeed on a DC 19 Dexterity saving throw or take 10 (3d6) fire damage at the start of its next turn.

The lava keeper makes four slam attacks. Alternatively, it can use its Lava Lob twice.

Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 25 (4d8 + 7) bludgeoning damage.