The Master of the Turbulent Timeways required players to get the Mastery of Timeways buff every week for 5 weeks. To get Mastery of Timeways, you need to do a total of 4 dungeons to stack the buff up to 4 before it expires. However, if you get the Mastery of Timeways buff and roll it over to next week, you only need to complete 1 dungeon the next week in order to get progress for the achievement.
As Mastery of Timeways doesn’t tick down while offline, you may wish to get the buff on a character you don’t play much so that you only need to do one dungeon each week!
When you complete all 5 weeks, you get the Sandy Shalewing Mount!