MSO – Mod for solar reflection.

Is this an overlay of light on the textures, or a separate effect? In simpler terms, will there be reflections in the dungeons?

The battle in the dungeon won't work; instead, a different battlefield is loaded (I don't understand how this is implemented; with the black dragons, the texture for sunlight and metallic reflection is the same, and there's no such issue). The texture acts as a filter – determining where reflections will appear, but the color of the texture determines what the reflection will look like. However, it doesn't differ much from metallic reflection in principle.