Creating icons / pins with layers
 

I have a number of icons and I was wondering if it's possible to mix them together. I can see that Blizzard merges different pins. For instance, some world quests are about killing more powerful monsters. Therefore, an extra dragon-like gold element is added to regular quest pins.

Is it possible to do similar with my custom icons? I would like to add e.g. shadow, or glow effect etc.