[Pirotess]

As I understand it starting items will be on the rare side and the routes should have the ability to randomize themselves to a certain degree so the situation you present should be very very rare. You will be able to help fight the trash mobs on the encounter route but its been speculated those will be triggered as you advance through the dungeon and will aggro on the triggering group first. The boss mobs, which were dubbed "golden mobs" a term that I think is kind of clumsy, will only be able to be engaged by the group which started the event.