Magmin

The magmin explodes when it dies.
Dexterity Saving Throw: DC 11, each creature in a 10-foot Emanation originating from the magmin.
Failure: 7 (2d6) fire damage.
Success: Half damage.

Melee Weapon Attack: +4 to hit, reach 5 ft.. Hit: 7 (2d4 + 2) fire damage. If the target is a creature or a flammable object that isn't being worn or carried, it starts burning.

The magmin sets itself ablaze or extinguishes its flames. While ablaze, the magmin sheds Bright Light in a 10-foot radius and Dim Light for an additional 10 feet.