WoWDB

Ahn'kahet: The Old Kingdom makes its return to current content via the Timewalking system introduced with Patch 6.2.  All players level 81 and above will be able to queue for the Timewalking version using the LFD tool when the special event is active.  The official highlights blog is here.  Don't forget to pick up A Frozen Path Through Time.

Fun trick if you are a death knight, and it works in all difficulties!  Please be considerate and warn your group - especially the healer - if you plan to attempt this.  Also, it can cause specific mobs to become stuck in evade in the ground or other shenanigans.

Keep a Plague Walker alive long enough that it casts  Aura of Lost Hope.  Cast  Control Undead on it, at which point a sizable portion of the instance aggroes and runs to your location. There are multiple Plague Walkers towards the beginning in the dungeon, so if it dies before casting the aura just find another one.  IMPORTANT NOTE:  All the aggro will be on the controlled plague walker, so be sure to pick up the mobs - particularly the ranged ones - or you will lose your new best buddy.

Why does this work? The aura has a radius of 99 yards, and since the plague walker is now hostile to all other dungeon denizens... ;)