Cetus

Cetus is the Greek sea monster sent against a coast and offered a royal victim chained beside the water. Later retellings sometimes replace it with a Kraken, but Cetus is the creature belonging to the older Andromeda story. Its whale-scaled body combines surf and stone, large enough to treat a harbor wall as the edge of its feeding ground.

Breakwater Maw: creatures in a 60 ft cone make a Quick save. A failure deals 5d10 bludgeoning and piercing damage and pulls the creature 20 ft toward the sea. A successful save avoids the damage and pull. Harbor Break: Cetus strikes a seawall, vessel, or stone platform within 80 ft. Creatures standing on it make Tough saves or take 4d10 bludgeoning damage as a 30 ft section collapses. A successful save avoids the damage but leaves the section collapsed.

The Offered Victim Freed: if the intended sacrifice is released and carried beyond the shore, Cetus loses 2 AC and must make a Mind save to pursue any other target.