Helium Moss Brick Wall

Background walls that light themselves are the cheap way to keep a room readable without hanging a torch on every column, and this is one of the brighter ones.

The catch is color. The glow runs through the whole rainbow instead of holding one hue, so it fights any build with a fixed palette and works best in rooms meant to look unstable anyway. It also reads at full brightness while sitting in an item frame, which is unusual for a wall and makes it usable as a display piece rather than only as backing.