Ocean of Dreams
The Ocean of Dreams is a place of wonder where the energies of the living and dead can interact together. This plane is not one of the material planes and thus exists solely as mutable energies which adjust their shape and intensity from interacting with entities who are within it. The general area of the ocean is a communal consciousness which is shared within the Aether of all living things, which individual spheres of influence called the Islands of Dreaming. Each island is that of a specific dream from a specific entity, most often a living being whose mind connects with this plane while they sleep. The islands seldom interact together, though many dreamers believe they are dreaming as one with another it takes an exceptionally strong connection to bridge the sea of Aether and connect to dreamers together naturally; bit it is possible.
This realm has many names, it is at times called the Land of Dreams and Nightmares or simply the Land of Nightmares, tales and legends associated with this place tell of unintentional visits or unwise practitioners of magic who travel to the ocean unawares of the dangers. Nearly every language of every race has a concept of this place and name for it, it is a place where dreams, thoughts, and past / future events can come together.
The earliest legends of exploration in the dream realm come from stories of a dark wizard using the realm to attempt to predict the future. Ultimately he met an untimely end, having spent years entering the realm via a form of astral projection, experimenting with physically entering the dream realm and was never heard from again. Though his notes survived and spawned several of his apprentices to continue his work along different veins.
This work tells that the ocean has some structure to it, while dreamers visit this place in their sleep (and when awake in rare times) by accident, their islands come and go and are never the same on two successive visits unless touched by an outside force. However, the living are not the only beings here. The Aether of the dead is also here and their islands are vast and far more powerful, these are static places that grow over times, each one expanding to meet those they knew in life once the Aether of a newly departed entity manifests here, it naturally comes into focus near those it knew in life who are also departed. These islands grow and can connect allowing the souls of the dead to share a dream should they wish. Since the entities control their islands they cannot be forced into a dream nor can they be forced to connect to another island.
Legends also tell that within this realm all fear, hate, and anger must be released to reside here. Those entities which die and cannot do this, are descended into the Severed Realm. This is not true for all energy which exists here, as there are dangerous entities which can touch the islands and feed off of negativity and other such things, turning dreams into nightmares.
Travel Through Dreams
Since this realm connects to all other realms in some way or another, it is possible - although unwise - to use it to travel between places. It is not without significant risks to do so. In any realm where thoughts and reality are mixed, one runs the risk of loosing track of what is real and what is not and this singular risk is one of but many. There are denizens of the Ocean of Dreams who reside here and feed off of the distress of others. Since this realm connects to all places, powerful immortal entities often use it as a way to move through between realms, unconcerned with what could rend a mortal into shreds. Such entities have even been known to speak with the dead or in very rare cases the living through their dreams. Such beings are transient and come and go as they please.
It was said that one could use their dreams and this realm to predict the future in the form of prophecy using a book called a "Sennik", while in modern parlance the this "dream dictionary" has contemporary meanings that are not supernatural or paranormal in origin having been replaced by psychological texts about the potential representations of images in a dream for a persons mental state. A true Sennik, however, is not a mundane book but rather a kind of book of the dream world, crafted specifically to record images and impressions of this special realm. It is crafted so that it is identical in both the waking world and the dreaming world, unlike most things which are not. Within the dream world it also has special properties and can be used to influence the world around it, imbued with either the psionic or magical energy of the person who created the book, it is an extension of its creator and will rebel against alien hands who attempt to pry into its secrets.
Those who are skilled in the use of a Sennik and thus in the world of dreams are often called Mistrzowie Koszmarów in the polish, though most cultures for which the exploration of the dream world developed independently have their own name and practices for a similar person, a master of the dream world, and the tools used by that person. In some cultures, a Grimour (the traditional spell book for a practitioner of magic in Western Europe (particularly in the areas surrounding Germany and France to the west and south) is said to be particularly potent in dreams and when constructed properly is able to be used in much the same way as a Sennik is.
Interaction with Reality
The material plane is closely tied to this plane, but of no particular reality. The Ocean of Dreams can reflect the real world, in part, though focused thought. Not only to the islands of the dead and the dreams of the living exist here but the worlds of the material plane do as well. Should one astral project here, an echo of the real world will be found first and that is where a person will come into focus. This dreamscape interacts with reality through the forces of creation and destruction. Here in the ocean, the Aether is mostly a force for creation, and some draw on that force of creation in the form of dreamessence, a focused magical energy derived from the Ocean of Dreams itself.
Since this echo of the real world is unstable and responds to thoughts of those in it the representation of the real world is manifest as the most static portions of the real world. As such a mountain range is nearly immutably solid but a single pebble is more ethereal in nature. The representation of the real world takes the form of the most common and static embodiments of different possible realities. This makes some objects nearly like ghosts and echoes but others more solid. Someone who is skilled with the use of magical energy and thoughts here can manipulate these echoes of the real world to cause changes in the material plane. Thus even living, or pseudo-living, entities can be created easily here with thought in the ocean itself and then brought to the real world through no small amount of skill as a homunculus or golem.
Further, some entities exist in both the ocean and the material plane, drawing their essence and energy from the dreamscape. Such entities are the Kithian, which are entirely based on the dream and able to use dreamessence to manipulate the real world and mortals through their dreams. A male kith can form a union with a female dreamer that impregnates her with a being that has the soul of a human and the soul of a Kithian. Such entities, Changelings, act as bridges between dreamers and the ocean; able to use dreamessence to affect the real world for wayfarer magic, locomotion, or even constructing fantastical contraptions impossible in the material planes.