Would be great having massive PvE HNM's more in the way that Guild Wars 2 has, you go to an area and then suddenly a giant Mob appears and requires lots of people to kill it not just a party, it could work if the game itself could make alliances at those moments, i dont want nothing like using artillery of any sort just players versus this HNM, the drops could go randomly to a general loot list with a need/greed system so at the end will be your luck the one that decides, and make those drops rare/ex so if you have any of those drops you cant vote at all on that item, and of course offering a good bunch of company seals too.

They could tie those events to npc's like Alfgar, after the HNM pops in the area (they could even make dramatic changes in the enviroment to impose fear) the npc instantly shouts in the city asking for help and give some time to start the event (in the meanwhile the HNM could be attacking a town or just making roars or whatever they think best lol), so at the end if they offer really good items you wont get short on ppl for those events, and everyone will get their random pop HNM's that are asking.