monster

The Ghost of the Swells

CR 20

Gargantuan undead, Neutral Evil

Reveal Stat Block

Armor Class

Hit Points

367 (25d20 + 105)

Speed

0 ft., fly 80 ft. (hover)

str

dex

con

int

wis

cha

Saving Throws DEX +11, WIS +12, CHA +14

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

Damage Immunities cold, necrotic, poison

Condition Immunities charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained

Senses darkvision 120 ft., passive Perception 16

Languages understands the languages it knew in life but can't speak

Traits

Incorporeal Movement.The ghost 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.

Spectral Dreadnought.The ghost is as large as an airship and can carry spectral crew or captured souls. It ignores difficult terrain and can move through enemy spaces without penalty.

Aether-Siphon Aura.Any creature that starts its turn within 60 feet of the ghost must succeed on a DC 21 Charisma saving throw or take 21 (6d6) cold damage and have its movement speed reduced by half until the start of its next turn. Additionally, any creature that fails this save loses its lowest level unspent spell slot.

Legendary Resistance (3/Day).If the ghost fails a saving throw, it can choose to succeed instead.

Actions

Multiattack.The Ghost makes three Aether-Chill Touch attacks or uses its Soul-Shattering Broadside.

Aether-Chill Touch.Melee Spell Attack: +15 to hit, reach 15 ft., one target. Hit: 28 (4d10 + 6) cold damage plus 18 (4d8) necrotic damage.

Soul-Shattering Broadside (Recharge 5-6).The Ghost releases a volley of spectral cannon-fire from its misty flanks. Each creature in a 120-foot long, 10-foot wide line must make a DC 21 Dexterity saving throw, taking 70 (20d6) force damage plus 35 (10d6) cold damage on a failed save, or half as much on a successful one.

Maelstrom of the Lost (1/Day).The Ghost conjures a massive swirling vortex of icy Aether in a 60-foot radius centered on itself. Each creature in that area must make a DC 21 Constitution saving throw, taking 55 (10d10) cold damage on a failed save, or half as much damage on a successful one. Creatures that fail the save are pulled 30 feet toward the Ghost and are restrained by spectral hands until the end of their next turn.

Legendary Actions

Spectral Surge.The Ghost moves up to half its fly speed without provoking opportunity attacks.

Touch of the Void.The Ghost makes one Aether-Chill Touch attack.

Fog of the Damned (Costs 2 Actions).The Ghost releases a thick, spectral fog in a 40-foot radius. The area is heavily obscured for creatures other than the Ghost. Any creature that starts its turn in the fog takes 10 (3d6) necrotic damage.

The Ghost of the Swells

The Ghost of the Swells is not a single spirit, but a monstrous amalgamation of the lost souls who have perished in the treacherous Aether currents surrounding the sky-cities. Taking the terrifying shape of a colossal, tattered galleon made of mist and spectral frost, this entity wanders the Broad Swells, a harbinger of doom for even the most heavily armed airships.

Mariners whisper that the Ghost is drawn to ships carrying large quantities of unrefined Aether, feeding on the magical energy to sustain its gargantuan form. Its "cannons" fire concentrated blasts of soul-chilling void energy, and its very presence can drain the life from a crew before they even see the ship in the mist.

Secret Motivation: The Ghost is unconsciously guarding the submerged wreckage of a legendary dwarven dreadnought that was lost centuries ago. The souls within the Ghost are bound to a cursed Aether-engine still throbbing in the depths, unable to move on until the engine is destroyed.

Adventure Hook: A wealthy merchant house hires the party to protect their flagship during a crossing of the Swells. During the expedition, they are stalked by the Ghost of the Swells, which is intent on dragging the entire ship into the spectral depths to join its eternal crew.