Quick rant...
The devs must have forgot to put something in this mission because I don't see how normal groups could ever finish without finding the trick on the internet.
The idea is you have to track the boss mob's whereabouts to make him spawn. You go to 20 individual locations in order and get emotes that indicate the boss was there but moved on. Basically you are one step behind the boss until you get all the emotes, when the idea is you caught up to him and can kill him.
The problem is that the emotes all say the same thing - basically "he was here, keep looking".
There is no indication whatsoever about where else to look next. You would think running around randomly might help, but the trigger spots are so narrow you have to be right on it to get the emote.
We cleared the entire zone of all mobs and all ran around the empty zone for about 40 minutes until one of our group members looked the mission up on the internet.
I'll say that the zone, Stillmoon Temple, is stunning. The mobs are very well made too. So, up until we cleared the zone it was a very fun and exciting time.
The zone and mobs were so good that the nearly impossible puzzle makes me think someone forgot something when releasing the mission.