Amalgamated Magma Mephit

Death Burst. When the mephit dies, it explodes in a burst of lava. Each creature within 10 feet of it must make a DC 18 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.

Eyes Everywhere. The amalgamated nature of the creature mean that it faces in every direction. It cannot be flanked and has advantage on Perception (Wisdom) Checks that rely on sight. 

Heavy! It has many wings but is too heavy to fly. This doesn't stop it from trying and those engaged with one may be amused to see it strenuously flapping its many ill-formed wings vainly.

Multiattack. The amalgamated mephit makes four claw attacks as an action.

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 4-6). The mephit exhales a 15-foot cone of fire. Each creature in that area must make a DC 13 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.

Innate Spellcasting (3/Day). The mephit can innately cast heat metal (spell save DC 9) as a bonus action, requiring no material components. Its innate spellcasting ability is Charisma.