Even by the current terrible standards of this game this is badly designed garbage.
Once you place the flag there's a number on it, like 0/100. You kill things and it will go up, but it goes down for some reason too. No idea why.;
For awhile non elite mobs were coming in to the circle and targeting me directly. Once I killed them it'd go up about 9, but stopped at 80/100 and no mobs came into the circle anymore. I killed a few mobs outside of the circle and that seemed to help, but the number would go down so much it wouldn't help enough.
If you leave the circle the number seems to go down faster.
Weirdly, if by some miracle you finish this quest, you have to go back to Daka.
Edit: as if this wasn't bad enough now, I do it and the mobs attack you so fast you end up dying (depending on the class you're on of course). Once you die it completely resets to zero... Seriously, who hires these people?
On the plus side it looks like you can do it with others and even share a tag now with the other faction (I'm assuming that's wm off only), so that helps. If you can do it while others are.doing it you're much better off. Though I've noticed that sometimes the sharing of kills doesn't work.
Edit2: So bizarre, I've done this quest now on several toons quite a few times and I still don't get it. It never seems to work the same way twice. I just sat there and killed all kinds of mobs inside the circle and probably one in 5 (20%) counted towards the flag. Why? Who knows?