Just ran through EoW Challenge in maybe 10 minutes tops but it's no longer giving out the Sense of Urgency achievement. (Killed Decoring the right way, it should have given the title and illusion clicky.)
i believe you gotta kill the last guy in the right order to get the achievement you cant just go in there and burn him super fast.
This is how I used to do it: Kill the first mob, it splits into two mobs. Kill those two initial splits before killing any of the mobs that those then split into. Finally kill off all the little guys that split off from the death of the initial splits. I'll try it again tonight but try killing them slower and see if I get it to work.
This is still broken. I ran another alt through and they were able to get the Decorin Bonewing [Challenge] achievement, but not the Sense of Urgency achievement and no title or illusion. I'm killing it the same way I've always done it for the achievement as I noted in the post above. I even made sure I didn't just one shot them in case killing them too quickly was breaking it.