Magma Form. The elemental can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 5 (1d10) fire damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 5 (1d10) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.

Magma Regeneration. While standing in lava/magma, the elemental regains 5 (1d10) hitpoints at the start of each of its turns.

Illumination. The elemental sheds bright light in a 10-foot radius and dim light in an additional 10 feet.

Water Susceptibility. For every 5 feet the elemental moves in water, or for every gallon of water splashed on it, it takes 2 (1d4) cold damage.

Multiattack. The elemental makes two slam attacks.

Slam. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage plus 5 (1d10) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Eject Magma (3/day).  Ranged Weapon Attack: +6 to hit, range 30/60, one target.  Hit:  25 (4d10 +3) bludgeoning damage plus 11 (2d10) fire damage. The elemental hurls a molten section of its body at a creature or object. Regardless of whether the attack hits or misses, on Initiative count 20 of the next round, the hurled magma magically transforms into a Magma Mephit.  The Mephit is friendly to the Elemental and will act independently of it on the elemental's turn. If the Mephit is still alive when the Magma Elemental dies, it dies as well, using it's Death Burst feature as it does so.