Chitin Host (Fire Beetle Variant)

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 insect. The swarm can’t regain Hit Points or gain Temporary Hit Points, unless encasing a host.

Encase. The swarm can encase the target (see attacks). While encased, the host becomes vulnerable to fire attacks while the swarm is resistant to them. 

Heat Aura. At the end of each of the chitin’s turns, each creature in a 5-foot Emanation originating from the chitin host takes 16 (3d10) Fire damage.

Illumination. The chitin sheds Bright light in a 10-foot radius and Dim light for an additional 10 feet.

Multiattack. The Chitin Host makes two Claw attacks, one Sting attack, or attempt to Encase.

Claw. Melee Attack Roll: +5, reach 5 ft. Hit: 10 (2d6 + 3) Slashing damage. 

Sting. Melee Attack Roll: +5, reach 5 ft. Hit: 7 (1d8 + 3) Piercing damage plus 11 (2d10) Poison damage.

Encase. On any successful attack the Chitin Host may attempt to grapple. If the target is a Medium or smaller creature, it has the Grappled condition (escape DC 14). Until the grapple ends, the target has the Blinded and Restrained conditions, is suffocating, and takes 10 (2d6 + 3) Bludgeoning damage at the start of each of its turns. The Chitin Host can smother only one creature at a time. The parasitic Chitin Host regains Hit Points equal to the amount of damage caused by the suffocation. The encased host becomes vulnerable to piercing damage. Heat Aura remains in effect.

Host Takeover. If a creature is reduced to 0 hit points by the Chitin Host’s Encase ability, the swarm fully integrates the host into itself. The Chitin Host gains temporary hit points equal to the host’s maximum hit points, and its size becomes Large. The Chitin Host’s Pincers damage increases to 14 (3d6 + 3) piercing damage and 7 (2d6) poison damage. While the host is integrated, the Chitin Host’s speed increases by 10 feet. This effect lasts for 1 hour, or until the Chitin Host is reduced to 0 hit points.

Parasitic Impregnation. If a creature reduced to 0 hit points by the Chitine Host's Encase ability is later healed and brought back to consciousness, there is a 50% chance that the host has been impregnated with Chitin eggs. After 24 hours, the host must make a DC 15 Constitution saving throw. On a failure, 1d4 Giant Fire Beetles burst from the host's body, killing it instantly. The swarms are under the Chitin Host's control (if it still exists) or act independently if the Chitin Host is destroyed.