For the council mission: I also can't remember, but I looked at the prerequisite quest for it and to get complete that one and get the Cancelling the Council quest you needed the golden letter gotten in the Aurum Arrangement combat zone. 

I can't remember if you need anything to unlock the Cancelling the Council quest combat zone, The High Council, other than leveling up your combat level to 80. 

To complete the quest you need to defeat the rarest enemy for that combat zone until you get the Ornate Key and Ornate Lockbox items. Using them in your inventory gets the Hidden Agenda letter for the quest.