I am trying to add a decal of glowing runes onto a sword blade.  The decal works fine.  I made a png layer over the texture map and attached it to "math functions" and then "blender" to combine with the original map.   It worked exactly as I expected.

Now I want to add ambient light to only the runes.  It is probably not too difficult to make the masked text glow, but I am having no luck so far.

This would also apply to text on a digital display.  Can anyone help me, or point me to a relevant thread?