Fuel Elemental

Flammable Form: This elemental is immune to fire damage, but will be caught on fire if attacked with fire damage. A creature that touches the elemental or hits it with a melee attack while the elemental is on fire takes 6(2d6) 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 while on fire, that creature takes 4 (1d8) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 3 (1d4+1) fire damage at the start of each of its turns.

Illumination: The elemental sheds bright light in a 20-foot radius and dim light in an additional 20 feet while on fire.

Douse: If the elemental walks through 5 feet of water or is covered in water while on fire, it is no longer on fire

Punch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage

Flaming Punch. Melee Weapon Attack: -1 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) 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 3 (1d4+1) fire damage at the start of each of its turns.