Brimstone Elemental

Fire Form. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 23 (3d8+9) 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 12 (2d8) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 12 (2d8) fire damage at the start of each of its turns.

Illumination. The elemental sheds bright light in a 15-foot radius and dim light in an additional 30 feet.

Multiattack. The elemental can make a Dash attack, and a HellBlast attack.

Dash. Melee Weapon Attack: +5 to hit, reach 25 ft., one target. Hit: 15 (3d6 + 5) fire damage and 7 (1d12) bludgeoning Damage. If the target is a creature or a flammable object, it ignites. The fire is Brimstone Fire, and cannot be doused. Instead, it takes 5 minutes for the fire to burn out itself.

HellBlast. Ranged Weapon Attack: +5 to hit, reach 30 ft., 5 targets. Hit: 5 (1d6 + 2) fire damage. It fires 6 fire bolts that home onto the targets if they are within 5 ft. of the bolt. Up to 4 bullets can home onto a single enemy.

The Brimstone elemental can move up to 15 ft. on every players bonus action. If it touches a target, the target must make a dexterity saving throw or be knocked back 10 ft.

Brimstone Shield (Usable every 5 rounds). The Brimstone Elemental can cover itself with brimstone, giving it advantage on constitution saving throws and +15 armour class until it's next turn.