One of the features coming in patch 6.2 is the Timewalker event. It’s one of 7 possible weekend events. One is for The Burning Crusade, and one is for Wrath of the Lich King. For the next few days the Wrath of the Lich King event is active on the PTR for testing. During the event there is a quest you can do to get 1 extra raid loot bonus roll coin that does not count towards the 3 per week cap. To get this you will have to do 3 (edit: now 5) random Timewalker dungeons. You can pick up this quest in your garrison.
Other than the quest the bosses also drop timewalker items that look like their original WotLK counterparts. These have the “timewarped” tag. At level 100 these have an item level of 660. If you do the timewalker dungeons as a level 90, these will have a 463 item level. You’ll be able to do timewalker dungeons if your level is atleast as high as the original dungeon’s requirement. This means level 70 for TBC timewalking and level 80 for WotLK timewalking. The item level of the loot will adjust to your level when it drops.
The dungeons available in the WotLK event are
- Ahn’kahet: The Old Kingdom
- Halls of Lightning
- The Nexus
- Utgarde Pinnacle