10. What is beyond the Wall? (So help me, any of you who makes some lazy-ass Game of Thrones reference is kicked out of the OSR.)
Assuming that the Wall you are referring to is the known landmark in the Astral Plane, it is a barrier between the waking and dreaming worlds. On one side of this wall of light are the astral projections and daydreaming souls of those who are still awake, while on the other side of the wall are the dreamers and comatose sojourners desperately searching for meaning in a chaotic and ever-changing landscape. Crossing the wall is relatively easy but takes a conscious effort.
The wall itself is composed of an ephemeral protoplasm known variously as "dreamstuff", "Arcadium", or one of a hundred other names. Every person who travels through the wall leaves a fragment of their soul in the wall, and finds it replaced by the material of the wall. It is said that those who travel through the wall often find their abilities to weave illusions enhanced, at the risk of finding their physical presence in the mundane world diminished...they gradually become illusions themselves, until the entirety of their soul is replaced by the material of the wall and an attempt to cross becomes their final moment...they become one with the wall.
It is said that there is a similar wall of darkness, dividing the living from the dead, but it is much harder to find and only able to be crossed via specific portals at certain times of the year. Those who attempt to cross this wall, gain a similar effect of augmented magic but with regard to necromantic effects. Over time they gradually become spectral entities, undead for eternity, losing their sanity as the dark wall calls them back.