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Mariner Ghost Swarm


AC 15 (natural armor)

HP 340 (40d12+80; bloodied 170)

Speed 0 ft., fly 50 ft. (hover), swim 50 ft.

Proficiency +4; Maneuver DC 13

Saving Throws Dex +6, Con +6, Int +6

Skills Insight +6 (+1d8), Perception +6 (+1d8), Stealth +6 (+1d8)

Damage Resistances acid, fire, lightning, thunder; bludgeoning, piercing, and slashing

Damage Immunities cold, necrotic, poison; bludgeoning, piercing, and slashing from nonmagical weapons

Condition Immunities charmed, fatigue, frightened, grappled , paralyzed, petrified, poisoned, prone, restrained, strife, stunned

Senses darkvision 120 ft., passive Perception 20

Languages Common

Elite Recovery (While Bloodied). The swarm ends one negative effect currently affecting it. It can use this action as long as it has at least 1 hit point, even while unconscious or incapacitated.

Ethereal Sight. The swarm can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa.

Incorporeal Movement. The swarm can move through other creatures and objects as if they were difficult terrain . It takes 5 (1d10) force damage if it ends its turn inside an object.

Swarm of Ghosts. The swarm can occupy another creature’s space and vice versa. The swarm can’t regain hit points or gain temporary hit points. Enemies can move through the swarm, which counts as difficult terrain .

Turn Resistance. The swarm has advantage on saving throws against any effect that turns undead .


Withering Cutlasses. Melee Spell Attack: +9 to hit, reach 5 ft., one living creature. Hit: 33 (8d6+5) necrotic damage plus 7 (2d6) psychic damage.

Magic Blast. Ranged Spell Attack: +9 to hit, range 100/300 ft., one target. Hit: 38 (6d10+5) force damage.

Etherealness. The swarm enters the Ethereal Plane from the Material Plane, or vice versa. It is visible on the Material Plane while it is in the Border Ethereal, and vice versa, yet it can’t affect or be affected by anything on the other plane.


Spirit Absorption. The swarm chooses one creature sharing its space, attempting to rend the target’s soul from its body. The target makes a DC 17 Wisdom saving throw , taking 42 (12d6) necrotic damage on a failure or half damage on a success. For the next hour, the target’s attacks deal full damage to the swarm (ignoring damage resistances ). If the swarm kills a target that has been damaged by this trait it is drawn into the swarm. Should the target be returned to life within the next hour it is freed from the swarm and the swarm is incapacitated for 1d4 rounds. After a target has been within the swarm for 1 hour it cannot be resurrected by any means.


Painful Wail (While Bloodied). When the swarm is damaged it bellows a painful wail. Each creature within 60 feet of it that can hear it wail makes a DC 17 Wisdom saving throw . On a failed save a creature takes 35 (10d6) psychic damage and becomes frightened for 1 minute. At the end of each of its turns, a frightened creature can repeat its saving throw to end the effect. On a successful save, a creature takes half damage and is not frightened.

Monster Type Description

Humanoids include a number of different intelligent, language-using bipeds of Small or Medium size. Humans and elves are humanoids, and so are orcs and goblins. Humanoids may employ magic but are not fundamentally magical—a characteristic that distinguishes them from bipedal, language-using fey, fiends, and other monsters. Humanoids have no inherent alignment, meaning that no humanoid ancestry is naturally good or evil, lawful or chaotic.