Overview
Poseidon is the god of the seas, oceans, rivers, lakes, and earthquakes. He also has the power to create new life, and is responsible for the creation of the bull and the horse. Poseidon is a possessive god, his waves constantly lapping at the land belonging to his fellow gods, breaking off a bit here and a bit there. Poseidon also has a terrible temper, and vents his rage in the form of storms or earthquakes. His churlish disposition causes his fellow gods to consider him foolish, but only the mighty Zeus would dare say so to his face. If any coastal community neglects his worship, he is quick to flood it with a tidal wave or smash it with an earthquake.
Description
Poseidon appears as a huge bearded man with long flowing black hair, wearing a tunic and carrying a trident. He is often accompanied by a retinue of merfolk, tritons, and sea nymphs.
Poseidon's true form is that of a hundred foot (30 meter) tall man.
Holy symbol
Poseidon's symbol is a trident.
Favored weapon
Poseidon wields a trident in battle.
Possessions
Poseidon possesses a trident that was created for him by the Cyclopes, which is capable of causing earthquakes on land and below the sea. Poseidon is able to impale an opponent on the barbed prongs of his trident. His victim is unable to escape unless pulled off by a companion (inflicting additional damage), or released by the god.
Realm
Great Wheel cosmology
In the Great Wheel cosmology, Poseidon resides within his realm, known as Caletto, which is located on Aquallor (also known as Ossa), the second layer of the Olympian Glades of Arborea. Caletto is a vast oceanic realm sprinkled with tiny uninhabited islands. The majority of the realm lies under the waves of Aquallor, and is astonishingly beautiful. Deep trenches hide cities of breathtaking splendour, and kelp forests wave and bob in the currents. Part of Caletto somehow borders the shores of Mount Olympus which is located on Arvandor (Olympus), the first layer of Arborea.
Olympian cosmology
In the Olympian cosmology, Poseidon resides within the outer planar realm of Olympus, a great mountain which stands at the center of the world. This mighty peak rises so high above the world, that its heights form a distinct planar realm. It serves as home to the majority of the Olympian deities, not including Hades, and each deity maintains their own personal domain within this realm.
Worship
Poseidon requires very little from his worshippers except sacrifices. His priests must throw a bull into the sea as a sacrifice at least once a month. They are also expected to bless the boats of fishermen, and at least one priest is usually taken along on any long sea voyage.
Omens from Poseidon take the form of storms, trembling ground, or visits from hideous, newly created monsters. When especially pleased with a priest, Poseidon rewards him with a warhorse similar to that summoned by a paladin, or by creating a spring in a place of the priest’s choosing.
In Spelljammer
The inhabitants of Greatspace revere the gods and goddesses of the Greek pantheon, especially Zeus, meaning that Poseidon can be considered a native deity.