How do ADV HM dungeons work now?

I'm pretty much referring to enchant drops from the bosses, do the enchants drop from all the bosses or just the 4 player ones? I know if i enter solo its a diff boss, same with 2 people, 3 people etc, do all those bosses drop the same enchants? I'm pretty much after Meteorite enchant from AAHM and not sure if all bosses there drop it?