The Veil

The Veil is a widely used term for the metaphysical, semi-permeable barriers that divide different realities from one another. While these conceptual walls largely keep universes separate, the reality on the other side can be sensed, or in some cases entered through the membrane. Realities separated by the Veil are typically parallel and close, but never actually touching.

The Great Veil and the Tear

Despite its grandiose name, there is little evidence that the so-called "Great Veil" is any different from any other, but it remains notable in its destruction. The Great Veil is often called "The Tattered Veil" or "The Sundered Veil".
In 0 SI, an interdimensional calamity, known as the Tear, sundered the veil between Bedouar and Old Elfriche. The cause of the Tear is still a subject of spirited debate, but its reality-warping effects have made final determination difficult. The Hud flooded into the mundane world of Bedouar, forever warping the land and its inhabitants, filling it with potent magical energy and upending the laws of physics. For Old Elfriche, the sudden impact of causality and solidity was far worse, akin to a ship striking a deadly reef. The home of the Fair Folk was almost completely destroyed in an instant, with refugees pouring out along the leylines to follow the life-sustaining magic that flowed into Bedouar.
What remained was reminiscent of a great flood that had breached a dam. After the deluge, both sides remained, but in great chaos. Bedouar, the valley below was flooded and destroyed, while the great lake of Faerie was drained, and replaced with a muddy riverbed. Parts of Old Elfriche survive, the Hud continuing to flow into Alvez from far beyond the veil, but true return to those far-flung regions remains elusive, separated by the infinite chaos of the Faewylde or other interdimensional planes like Mag Mor. Only one point of direct connection, the inaccessible Black Castle of Rupes Nigra, is known, although others may exist.

Manifestation

The Veil is not a physical barrier, but rather a conceptual divide between realities. As a result, it takes on many forms. For the most part, the Veil is invisible, inaudible and intangible, a robust divide that allows multiple realities to exist within the same conceptual space. In other places, the barrier is thin, allowing the other side to be perceived, interacted with, or entered. These regions of thinness are also called Bleed.
In its most obvious incarnations, the veil will appear as an actual barrier, a shimmering translucent wall of rippling atmosphere. Such flagrant barriers are rare, betraying a dangerous magical instability behind them. More common, the Veil will appear as a more mundane barrier. A stone wall, a line of trees, a cave entrance, and other such liminal spaces. To most passerby, the barrier will attract no attention, Passing around, over or under these barriers will merely reveal more of Bedouar behind it.
Only by passing through the barrier can the Bleed be entered. These entry points often reveal themselves as some expected opening, such as a passage between two standing stones, an old brass gateway in a passed over alleyway, an arch of intertwined trees, circle of mushrooms or even a forgotten door in an old house. These entryways are not typically stationary, and shift regularly in location and form. They are typically, but not always, blended in to their surroundings to the casual observer, but become more detailed and unique upon close inspection. Because these entry points are purely conceptual however, they may not exist upon turning around after crossing the threshold, having moved elsewhere. Unlike in Bedouar, exit points in Faerie are typically overt and out of place, like a gate sitting in a field, a door in a tree or a curtain hanging in a forest.

Localization

The Veil is ever-present in Alvez, but thinness is most apparent in transitional and liminal spaces. Mountains (between land and sky), Islands (between land and sea), forest edges and caves are all common spaces to experience thinness, but even in cities alleyways, side streets, doorways and river-quais can host passageways between the worlds.
While Old Elfriche is inaccessible from Alvez, regions of Bleed have stabilized into semi-permanent magical regions that are collectively known as Faerie. Regions where the flow of Hud is still actively warping reality are called Fisher Kingdoms