Most zones have two group missions in them (each of which is required for the "Hero of _____" Achievements), however actual progression involves only one mission per zone.
You must be at least Level 80 to participate in House of Thule tasks and missions.
You must be at least Level 87 to request most of the T3 tasks and ALL missions.
You must be at least Level 88 to request all of the T4 tasks and missions.
Listed below here are progression tasks by zone. Bolded tasks (each of which is a group mission in an instanced zone) are required for everyone. Unbolded tasks are required only to request the group missions.
You must be at least Level 80 to participate in T1 tasks and missions.
You must be at least Level 87 to do most of the T3 tasks and ALL missions.
You must be at least Level 88 to do all of the T4 tasks and missions.
ALL missions (apart from Morrells Ascendant) can be joined at level 80. You won't be able to request them (as you cannot do some of the solo tasks), but you can get added, enter the instance and get credit for them.
You only have to be level 75 to participate on Progression Tasks. I have done the first 4 with my level 75 and the last Fear mission at 76. I did try to get the "rot dogs" solo task in lower hot at 75..but I was too low. Perhaps this is why some think you have to be higher level to do progression?
Didn't mind the progression stuff on the 2 sites posted but tried my best to sort out miragul's theme. I believe i have them all but i don't remember if there is an order to do them.
Thanks :) will have to check those out. My notes around a bit out of order for T3 & 4 so hopefully the T3 stuff i posted is correct. For the life of me i can't find the miraguls theme stuff i had. Will have to look harder i guess. As for T4 Still going through notes on that stuff too
Anyone updating this wiki please note that the info i have posted for up to House of thule (upper floors) Is from beta. If anything has changed since then please correct it :) I have the missions/requirements for the rest of the zones and i will update them when i get my notes in order....