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    Bulgasari 불가사리

    Huge monstrosity, unaligned

    Armor Class 20 (metal-infused hide)

    Hit Points 310 (23d12 + 161)

    Speed 40 ft., burrow 10 ft.

    STR 26 (+8) · DEX 10 (+0) · CON 24 (+7) · INT 3 (−4) · WIS 14 (+2) · CHA 7 (−2)

    Saving Throws Con +13, Wis +8

    Skills Perception +8, Athletics +14

    Damage Resistances bludgeoning, piercing, and slashing from non-magical attacks; the same damage from metal weapons, even if magical

    Damage Immunities poison

    Condition Immunities charmed, exhausted, frightened, poisoned, prone

    Senses darkvision 120 ft., tremorsense 60 ft., passive Perception 18

    Challenge 17 (18,000 XP)

    Traits

    Impossible to Kill. When Bulgasari is reduced to 0 hit points, it doesn’t die until the end of the next round, and only if it took at least 40 fire damage or 40 radiant damage since the start of its prior turn. Otherwise, it regains 100 hit points and ends all conditions on itself.

    Devour Metal. Whenever Bulgasari deals damage to an unattended metal object or ends its turn grappling a metal-armored creature, it destroys or warps part of that metal and gains 20 temporary hit points.

    Feed on Steel. When a creature hits Bulgasari with a metal melee weapon, Bulgasari gains temporary hit points equal to half the damage dealt by the weapon (rounded down). If the weapon isn’t magical, the attacker must succeed on a DC 18 Strength saving throw or the weapon is destroyed.

    Fire Paradox.

    • Weakness. The first time Bulgasari takes fire damage in a round, it has disadvantage on attack rolls until the start of its next turn.

    • Fury. If Bulgasari suffers fire damage on two consecutive rounds, its hide glows red-hot; until the end of its next turn its melee attacks deal an extra 10 (3d6) fire damage.

    Siege Monster. Bulgasari deals double damage to objects and structures.

    Actions

    Multiattack. Bulgasari makes three attacks: one with its Bite, one with its Gore, and one with its Tail.

    Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 29 (4d10 + 8) piercing damage.

    Gore (Elephant Trunk & Tusks). Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 25 (4d8 + 8) bludgeoning damage. If the target is a creature, it must succeed on a DC 19 Strength saving throw or be pushed up to 15 feet and knocked prone.

    Tail Swipe. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 23 (4d6 + 8) slashing damage.

    Needle Back (Recharge 5–6). Hundreds of iron-hard quills erupt in a 30-foot cone. Each creature in the area must make a DC 19 Dexterity saving throw, taking 45 (10d8) piercing damage on a failed save, or half as much on a successful one. Metal-armored creatures make this save with disadvantage.

    Bonus Actions

    Rampaging Charge. Bulgasari moves up to its speed in a straight line. If it ends this movement within 5 feet of a creature, it can make one Gore attack against that creature.

    Reactions

    Catch and Consume. When a non-magical metal projectile (arrow, bolt, bullet, or thrown weapon) would hit Bulgasari, it instead is destroyed on impact and Bulgasari gains 10 temporary hit points.

    Lore

    Literally “impossible to kill.” Born from a grain of rice, it grows immense by devouring metal. It has an

    Bulgasari (불가사리) is more than a beast; it is a symbolic reflection of the turmoil that marked the transition from Goryeo to Joseon. Everything about Bulgasari—its origin, appearance, growth, and even the ways people try to banish it—reveals the worldview and fears of those who lived through that upheaval.

    Many traditions agree that its name comes from the phrase bul-gasal (不可殺), “impossible to kill.” That invincibility stems from Bulgasari’s unique power: it devours metal, and each bite turns its body as hard as steel, immune to any weapon. The message is clear. Weapons—tools of control—only strengthen the monster, symbolizing the impotence of authority in the face of chaos and the public’s frustration with rulers who cannot solve society’s problems. The saying “Bulgasari appears at the end of a dynasty” refers to uncontrollable destruction and foretells the collapse of the old order.

    From Korean Bestiary 5E, p. 18 · Fern Flower Press