This achievement became available about 10 hours ago (or about 5am for my timezone), while not exactly the most difficult thing ever, it's pretty tedious.
16 territory related tasks (2 gold, 4 silver and 10 bronze) get added to the campaign every week for 10 weeks. (it's Ghulvania this week etc)
The tasks seem to randomly generate for the tiers. (i had a silver 'dungeon run' task last week, and a bronze one this week)
For the many bronze level 'win a match with this team/weapon/class' tasks, it's easiest to do an explore run at a level you're capable of (or a level 2 run which is quicker and gives more guild seals). the 'matching gems 300 times' one will come with time and the 'kill 44 of a type of enemy + kill a certain mythic 3 times' is easiest in the current weeks guild event but can be found in mythic explore battles and pvp if you're behind the current weeks event.
Or you can ignore all this and skip tasks with gems if you're rich (i only skipped silver tasks atm due to the limited playing time i have due to work) Bronze tasks cost 50 gems to skip, Silver cost 100 gems and Gold cost 150 gems to skip (thanks to Shadykilla420 and ArchBehemoth08 for the update)
I'll update this as i learn more, if you have any questions - feel free to ask :)
(p.s - the elite pass won't help with this achievement, but it will give you a lot more added goodies)