Long ago, the immortal being known as Zugzul spoke to his chosen priests, describing the method of creating an a fell device that could be used to destroy a god. It was called the Well of Souls. Throughout the centuries it has taken many forms, sizes, and shapes but its sole purpose is deicide. It exists only to unmake that which is immortal.
Efreet and Djinn came to aid in its forging, and many powerful spells would be woven into it. But the key to its power would be the lives that it contained, for only by the imprisoning of souls within its structure could the artifact be made to work. No true ritual was needed for the device to function, simply being in the area of war, murder, or genocide would fuel the artifact with the Spark of Life allowing it to manifest its mighty abilities.
Many have tried to find a way to unmake the Well. It’s powers are many, and it is somehow connected to the powers of the Shadowfell. The very nature of the artifact strikes terror into the mind of many throughout the multiverse. Who would not fear the power to kill a god? And yet, before his death, the Seer Alaundo pronounced a prophecy that the Well could only be unmade by the the hand of one not yet born. This angered many sages, saying that such a thing was impossible.
When the device is used, it vanishes and returns to the Shadowfell. When this happens, it changes its nature enough to become something entirely different, making it difficult to find. In the past it has been a ring, a sword, a book, and a crown. It is hard to predict what form the Well may take at any certain time and place once it returns to the darkness of the Shadowfell.
The Shadowfell is one of the more accessible planes. In fact, on rare occasions, travelers have stumbled into it by accident. Places where the boundary between the world and the Shadowfell are thin are known as shadow crossings. Some intersections are naturally occurring, the result of ancient planar conjunctions or catastrophes. These crossings often occur in low-lying, deeply shadowed spots—forested hollows, mist-blanketed bogs, or the bottoms of caverns and ravines. Other junctions form in places where the forces of death are prevalent—graveyards, battlefields, and other places that bore witness to mass death.
The Well of Souls is one device which allows for transport into other dimensions through the shadow crossings. When active, shadow crossings permit travelers to shift from the mortal world to the corresponding location in the Shadowfell (but not always back again). Few shadow crossings are continuously active. Most activate only under the right conditions, such as certain times of day, certain days of the year, or when various celestial phenomena take place—eclipses, new moons, or a solstice for example.
Sages claim there is a tome called The Book of Lacc that contains lore about these shadow crossings that intersect on the Planes of Existence. The book has been lost for centuries, hidden by a order of monks known as the Golden Flame.