Grand Hunter

I sometimes have trouble "finding" the hunt for the weekly quest.
I found this little tip on Reddit.

Open your map and click on the dragon in the bottom right corner. Select Maruuk Centaur. That will highlight all of the opportunities for rep for that group. Go to the horn and you are there.
No more flying around the area and hoping to stumble upon it.

Or maybe that was just me

To complete this achievement, you must talk to Tomul to start the hunt, participate in all sections of the hunt, and then talk to him again to end the hunt. Must open and close the hunt yourself.

EDIT: May no longer be the case, my alt got the achieve as well Dec 8 without talking to Tomul.

So I was in Dragonscale Basecamp while the hunt was happening near me, and since I was in the hunting zone and even though I did not do anything I got the achievement.