Refer to the bottom portion of the post brother :) The rare possibility of an extra "Boss-Specific" loot drop, similar to that of the elemental primary drops of Skolas.

I did read it but we'll still never know for sure?... It could also mean a guaranteed exotic or something? It's exciting to think about what it could mean if it really is a black engram. ;-) good post by the way dude... I would have never noticed that in the pic if i would've seen that pic until now. ;-)