Swarm of Fire Dancers

Elemental Nature. The swarm of fire dancers doesn't require air, food, drink, or sleep.

Fire Form. A creature that touches the swarm or hits it with a melee attack while within 5 feet of it takes 5 (1d10) fire damage. In addition, the first time the swarm enters a creature's space on a turn, that creature takes 5 (1d10) fire damage and catches fire. Until a creature, which can include the target, uses an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.

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

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny Elemental. The swarm can't regain hp or gain temporary hp.

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

Multiattack. The swarm of fire dancers can use its Frightening Visage, if available. It then makes two Singe attacks.

Singe. Melee Weapon Attack: +8 to hit, reach 0 ft., one target in the swarm's space. Hit: 22 (4d10) fire damage, or 11 (2d10) fire damage if the swarm has half its hp or fewer.

Frightening Visage (Recharge 5-6). The swarm rearranges itself into the shape of a giant, blue, flaming Humanoid skull. Each Humanoid within 30 feet of the swarm that can see it must succeed on a DC 16 Wisdom saving throw or be frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.