Death Burst. When the mephit dies, it explodes in a burst of lava. Each creature within 5 ft. of it must make a DC 11 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.
False Appearance. While the mephit remains motionless, it is indistinguishable from an ordinary mound of magma.
Innate Spellcasting. The mephit can innately cast heat metal (spell save DC 10), requiring no material components. Its innate spellcasting ability is Charisma.
Actions
Claws. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 3 (1d4 + 1) slashing damage plus 2 (1d4) fire damage.
Fire Breath (Recharge 6-6). The mephit exhales a 15-foot cone of fire. Each creature in that area must make a DC 11 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.