Dunno if people know already, but thought I'd share it anyway. Go to the top of the tower where the rare Commander Krag'goth spawns. There are two maps on two pillars, and clicking each of them gives you 5% completion.
Now open up the group finder and go to the questing section of premade groups. Join random groups, and every time you get invited you'll end up on a different server with the two maps up again, ready to get clicked.
Do this 20 times, and voila, complete. It's faster than killing mobs and running around all the time. Also, you have a chance that on one of the servers Commander Krag'goth is up, so you can kill him for even more % and Tainted Apexis thingies.