Sea God

The Sea God's full body is never wholly revealed, yet it is vast enough that tearing itself free shattered the entire island that caged it. Countless tentacles sprout from every part of its bulk, each splitting into still more limbs, and its cavernous jaws open onto a churning interior. At its center sits an eye-studded heart resembling the core of the Idea of Evil. A statue carved in its likeness depicts one of the primeval gods that humanity forgot, faded into the depths of the astral world.

Its signature power is assimilation. Anything it swallows becomes a tentacle-like appendage while keeping its original shape and even a sense of self, as happened to the Captain Sharkrider pirates, though the converted feel their lower halves go numb. The creature radiates a spiritual pressure so heavy that it smothers the powers of nearby spirits, and on full-moon nights it stretches its limbs far from the island to drown fishermen.

Its innards form a living fortress. Isopods, spider-like vermin, sharks, hagfish, and lamprey dwell within as both symbionts and guardians. Most dangerous is its heart, which fires waves of kinetic force through its inner muscle as a deliberate weapon; the pulses batter Guts so severely that he cannot close in to strike, robbing him of balance and direction. Its one exploitable weakness is the song of the merrow, which stills the deadly heartbeat.

Ages ago the beast fed on every living thing within reach until a tribe of merrow cornered it and sealed it inside an island cave. The frightened islanders declared the cavern taboo and came to regard the thing as a dreadful god that sank ships and ate people, even turning against the merrow who had protected them. After the Great Wave of the Astral World swept the world, the creature grew strong enough to consume the Captain Sharkrider vessel, its crew, and the villagers, folding them all into its mass.

When it menaces the Seahorse and those aboard, Guts resolves to attack from the inside and enters through its mouth with Schierke projecting alongside him as a guiding light. The two press up through its stomach and fight past the horrors nesting within while the crews battle the tentacle-slugs outside. As the monster rips free of the island, a massive wave washes Isidro overboard and drives Isma to awaken her own merrow blood. A gathering of merrow then raise their song, quieting the weaponized heartbeat long enough for Guts, blind and reeling but steered by Schierke, to rupture the heart and leave the leviathan floundering as it spills the ships trapped in its body.