Bone Ship

Gargantuan undead, chaotic evil

Armor Class 18 (natural armor)
Hit Points 297 (17d20+119)
Speed swim 60 ft.

28 (+9) 16 (+3) 24 (+7) 11 (+0) 17 (+3) 19 (+4)

Saving Throws Str +15, Con+13, Wis+9
Damage Resistances necrotic
Damage Immunities poison
Condition Immunities charmed, exhausted, frightened, poisoned
Senses darkvision 100 ft.; passive Perception 13
Languages Common (can’t speak)
Challenge 18 (20,000 XP)

Special Traits

  • Blood Wake. The frothing, churning waters around a bone ship are stained crimson with blood. Creatures that begin theit turn within 40 feet of the bone ship must make DC 18 Constitution saves. Those that fail become frightened. Targets that are frightened cannot use reactions and can use either an action on their turn or a bonus action, not both. Creatures can attempt a new save at the start of each of their turns to resist this effect. Those that succeed at their saving throws are immune to the bone ship’s aura for 24 hours. This works only when the bone ship is in the water.
  • Bound Souls. The souls of numerous sailors and sea creatures form the bone ship’s collective consciousness and hull. A bone ship is immune to spells and effects affecting a specific number of creatures. Any creature attempting to communicate with a bone ship, such as through telepathy, hears only the anguished cries of the imprisoned souls and must succeed at a DC 18 Wisdom save or contract longterm madness.
  • Turn Resistance. The bone ship has advantage on saving throws against any effect that turns undead.
  • Unholy Repair. By spending 1 full day inactive, the bone ship can heal itself to full hit points by scavenging the bones of dead sea creatures within a 10-mile radius, pulling the bones up from the bottom of the ocean to join its hull.


  • Multiattack. The bone ship attacks four times with bone cannons.
  • Slam. Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 45 (8d8+9) bludgeoning damage, and the target must succeed at a DC 18 Constitution saving throw or take 10 (3d6) necrotic damage.
  • Bone Cannon. Ranged Weapon Attack: +15 to hit, range 100/400 ft., one target. Hit: 30 (6d6+9) bludgeoning damage. The cannons are considered to be part of the bone ship and not separate objects.
  • Ghostly Boarders (Recharge 6). The bone ship disgorges the souls of the sailors bound within it. The ghostly boarders appear as spectral entities and slaughter all living creatures in a 60-foot sphere around the bone ship. Each creature in that area must make a DC 18 Constitution saving throw. A target takes 28 (8d6) necrotic damage on a failed save, or half as much damage on a successful one. Creatures reduced to 0 hit points in this manner are killed, their souls dragged into the bone ship, and can be restored to life only by a wish spell, or if the bone ship is destroyed.
  • Spectral Energy Cannon (Recharge 4-6). The bone ship can combine all four of its bone cannons into a spectral energy cannon, blasting a line 100 feet long and 5 feet wide. Each creature in the line must make a DC 18 Dexterity saving throw. A creature takes 63 (18d6) necrotic damage on a failed save, or half as much damage on a successful one.


Predators of the oceans, the hulking undead monstrosities known as bone ships leave devastation in their bloody wakes.

Formed from the collective consciousnesses of dead sailors bound within the bleached bones of giant aquatic creatures, bone ships hunt the seas without mercy, destroying ships and slaying the living wherever they are encountered. Bone ships stalk their prey with tenacious intelligence and single-minded purpose. They often trail their quarry for days, relishing the terror their sudden appearance on the horizon causes, and have even been known to continue the chase on land, the many bones of their hulls pulling them over the ground.

Bone ships do not care for plunder, seeking only to add more victims to their unholy crews.

The creation of a bone ship can occur in many different ways. Some bone ships arise as servants of evil gods, pawns to their vile wills. Certain powerful necromantic rituals can also create bone ships. Such rituals typically require those performing them to sacrifice dozens of humanoid creatures and trap the victims’ souls. Other bone ships result from ships being destroyed in horrific and catastrophic events. The souls of the sailors who died in such a disaster, unable to find peace, slowly form a bone ship on the ocean’s bottom before rising to the surface to take vengeance on the living. No matter how they’re created, bone ships retain jumbled memories of the previous lives of the souls bound to them-though all bone ships attack any creatures they encounter, each ship’s unique origin and collection of souls burns a particular objective into its very nature. A bone ship created by an evil god might target ships bearing the flags of an opposing faith or enemy of that god, while a bone ship created in a ritual is ingrained with a specific purpose that forces it to enact its creator’s will.

Certain bone ships viciously target ships from one or more nations, either those from the dead sailors’ former nation if they seek revenge, or those from a rival nation the sailors hated in life.

Over time, legends and stories about a bone ship’s capacity for destruction arise. A bone ship never takes a name for itself but living sailors may ascribe it an epithet based on its origin, purpose, unique characteristics, or notable attacks. Though all bone ships possess the same abilities, a particular bone ship can be identified by its hunting area and appearance.

Bone ships eventually display certain unique features such as glowing barnacles that cover its hull, a masthead featuring the skull of a particular sea creature, the bones of a unique and rare sea monster, or an unusual configuration of the musculature holding together its hull. Many of these changes are the result of a bone ship scavenging remains off the ocean floor to repair itself.

Lone Ships. No living crew-or even other undead creatures-have ever been seen sailing in a bone ship.

These undead ships operate independently, and don’t form alliances even with others of their kind. Merely attempting to communicate with a bone ship is dangerous, as even such means as telepathy produce only the howling voices of the suffering, ghostly crew, spreading their insanity to those foolish enough to contact them.

Modular Shape. Though a bone ship is a single creature, the numerous souls it contains create a hive mind. A bone ship can reshape certain aspects of its hull by using its knotted muscle to move the bones within it. This transformative ability allows a bone ship to quickly sprout cannons from its hull that can attack in any direction, and each ship keeps a collection of bones and debris within its own body to use as ammunition. It can also tap into the unholy energy giving it unlife to fire a devastating beam of negative energy at its enemies, and those who close with a bone ship find that even its hull has the ability to drain away life force.

Section 15: Copyright Notice

Sea Monsters (5E) © 2021, Legendary Games; Authors Michael Ritter, Michael “solomani” Mifsud, Robert J. Grady, Mark Hart, Jeff Ibach, Alex Riggs, Scott D. Young, Jeff Lee, Matt Kimmel, and Jason Nelson.

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