Fire Form. 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.

Illumination. The elemental sheds bright light in a 30-foot radius and dim light in an additional 30 feet.

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

Multiattack. The elemental makes two touch attacks.

Touch. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 20 (4d6 + 10) 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.

Fire Boulder. Ranged Projectile: +8 to hit, reach 30/120 ft., one target. hit:  25(3d10+10) bludgeoning damage. every creature within 15 ft. must succeed a DC 20 Dex save taking (4d6+6 Fire damage) taking half if saved.

Legendary resistance: 3/Day it can automatically save a failed save.

Fire Storm: every creature in a 60 ft. Radius must make a Dex saving throw of 24 or be ignited on fire taking 10D6 Fire damage or half as much if saved.