Golsaengchung 골생충

Tiny fiend (demon), unaligned

Armor Class 18 (natural armor)

Hit Points 90 (20d4 + 40)

Speed 10 ft., climb 10 ft., burrow 5 ft. (bone only)

STR 5 (−3) · DEX 18 (+4) · CON 14 (+2) · INT 2 (−4) · WIS 14 (+2) · CHA 6 (−2)

Saving Throws Dex +7, Con +5

Skills Perception +5, Stealth +9

Damage Vulnerabilities fire

Damage Resistances bludgeoning, piercing, and slashing from non-magical attacks

Damage Immunities poison

Condition Immunities charmed, frightened, poisoned, prone

Senses darkvision 60 ft., blindsight 30 ft. (while inside another creature), passive Perception 15

Challenge 6 (2,300 XP)

Traits

Bone Burrower. The golsaengchung can enter the body of a Large or smaller creature and stay there. While inside another creature (its host) it has total cover against effects that originate outside the host.

Demonic Resilience. The golsaengchung has advantage on saving throws against spells and other magical effects.

Life-Marrow Drain. While the golsaengchung is latched onto or inside a creature, that host can’t regain hit points, and it takes 7 (2d6) necrotic damage at the start of each of its turns.

Vital Weakness. A host reduced to 0 hit points by Life-Marrow Drain dies instantly as its life-force is consumed. The golsaengchung then emerges in an adjacent unoccupied space.

Infestation Removal. A greater restoration, remove curse, or comparable magic ends Life-Marrow Drain and forces the parasite to detach and fall prone at its host’s feet. A creature can attempt primitive surgery as an action: it makes a DC 16 Wisdom (Medicine) check on an adjacent host. On a success, the parasite detaches, and the host takes 14 (4d6) slashing damage; on a failure, the check has no effect.

Actions

Piercing Proboscis. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 9 (2d4 + 4) piercing damage plus 14 (4d6) necrotic damage, and the target is grappled (escape DC 16). Until the grapple ends, the golsaengchung can’t attack a different creature.

Burrow Inside. The golsaengchung ends its grapple and burrows into its host’s bone. While inside, the host is subjected to Life-Marrow Drain, and the golsaengchung moves with the host. The parasite can have only one host at a time.

Lore

A parasitic worm that lives in the human bone marrow. Victims suffer agonizing pain; the parasite can

Word reaches your party that a prominent city official has been infected with the Golsaengchung parasite, and traces of dark magic have been detected. You can take part in saving this honored citizen by tracking down a shaman and assisting him during the ritual dances.

The name Golsaengchung is made up of two syllables. The first, gol (골), means “bone” or “bone marrow.” The second, saengchung (생충), is a general term for “parasite” or “worm.” Taken literally, the monster’s name is “bone parasite.”

From Korean Bestiary 5E, p. 46 · Fern Flower Press